kyphysics
I've had some mold in my shower and even my car this past year (long story, but I HIGHLY suspect my car mechanic caused it, by leaving a nasty greasy residue on my fibers...).

I also have allergies and eczema. They causes itchy rashes (though usually very manageable by avoiding certain things and using topic Desonide cream). Had some bacterial infection too not too long ago (probably from me scratching my eczema too much and having it get infected).

1.) With germ-killing capacity (ultraviolet germicide)
2.) With "harmful particle"-killing capacity (i.e., anti-mold spore HEPA filters)

a.) The "good ones" cost $100+ (which, for me, feels like "a lot"...at least, right now it is) b.) Wondering if there are any cons/negatives I don't know about, such as ...maybe the ultra-violet thing easily catches fire or something? ..Or some other crazy hazard. c.) Would you have to buy like a bunch of these to really be effective if you have lots of rooms to your house/apartment/condo, in which case that'd be hundreds of dollars. Anyone have experience with one of these air purifying machines? Worth it for you? Any risks/dangers? Thanks! ETA: Saw this Time article, which says to avoid the ionizing air purifiers, because they cause health problems. http://time.com/4773089/air-purifier/ Last edited: ## Answers and Replies Science Advisor Gold Member 2021 Award I've had a good Honeywell for several years and it's good for taking dust out of the air. It has a "germ" mode and an "alergen" mode but I have no idea if they are effective. I don't think$100 is particularly high for a good one. In fact, it's really on the low end.

berkeman and russ_watters
kyphysics
Honeywell - Just came back from a late night Walmart shopping trip. Saw that they have Honey Wells, Thera-something, and an ionizing purifier.

They Honeywell machines cost $159 and$179 from what I saw. I haven't read online reviews to know if these are considered the "good ones," but they were the most expensive. I saw a $59 and$89 one too.

BUT, I read that what you want is the ones with a HEPA filter. I saw reload packets (2-pack bundle) of the filters, which cost something like $29.99. I've had a good Honeywell for several years and it's good for taking dust out of the air. It has a "germ" mode and an "alergen" mode but I have no idea if they are effective. I don't think$100 is particularly high for a good one. In fact, it's really on the low end.

Do you reload filters more than 2x a year, phinds?

I spent $40/tube (3x/year...for a total of$120) on Desonide cream last year for my allergy rashes, so that alone might cover the cost of the filters!

Gold Member
The thing about mold (and insects like silverfish, cockroaches, etc), is they all need a relatively high humidity, generally 60% or higher. A frequent recommendation is ideally below 50%. Many people are uncomfortable below 55%, and below that you may get static electricity sparks after walking on a carpet.

My wife and I live a few blocks from the Pacific Ocean with high humidity, especially at night. For decades we have used a portable Dehumidifier (about $160 at Home Depot) rated for 70 pints per day in 700 to 800 sq.ft. apartments. We typically run it on automatic for 8 to 10 hours during the day, maintaining around 52 - 55% Relative Humidity, and shut it off at night. The humidity in the morning is usually in the 65 - 75% range and the dehumidifier runs for a few hours and then starts cycling to maintain the set-point. The first week or two you have one it will likely run almost continuously to dry out the furniture, carpet, and clothing. Here in California with the high Electricity prices ($0.20 - $0.25 per kWH), it costs about$25 - $40 dollars a month to operate. In the Summer we have to run the air conditioner too because there is a lot of waste heat from the dehumidifier. There is also an exhaust fan in the bathroom that gets turned on when showering, other than that it isn't used much because it draws in the damp outside air. Since we don't use the kitchen stove much, we also partially sealed the range hood exhaust with Aluminium foil. If you have forced air heating/cooling be sure to change the filter every two or three months, and use a filter rated for pollen and allergen blocking. They cost about 10% more than the cheap ones (the local Walmart carries them here). A possible substitute for the Desonide if you are having a fungal problem is Boric Acid (Sodium Borate Decahydrate, it's sold as Ant and Roach powder in hardware stores). Be sure to get 99% or better purity without any other active ingredients, you don't want insecticide in it. You can sprinkle the powder in shoes, gloves, etc to keep the fungus under control; also in nooks and crannies in the bathroom to kill any mold. I use a concentrated solution in a spray bottle on my feet, and on my fingers as needed. Probably not a good idea to use it on large areas though. Mix some in warm water and shake until no more will dissolve then add water until it does dissolve. It tends to clog the spray nozzle so occassional maintenance is required. Just don't use it on broken skin, in your ears or eyes. Boric Acid is fairly safe, in weaker concentration it used to be the go-to solution for eyewash. (see: https://en.wikipedia.org/wiki/Borax) Cheers, Tom p.s. I just checked the log for the dehumidifier, 229 kWH over 1525 Hours, or 112kWH per month. This place is sealed pretty well though. kyphysics My wife and I live a few blocks from the Pacific Ocean with high humidity, especially at night. For decades we have used a portable Dehumidifier (about$160 at Home Depot) rated for 70 pints per day in 700 to 800 sq.ft. apartments. We typically run it on automatic for 8 to 10 hours during the day, maintaining around 52 - 55% Relative Humidity, and shut it off at night. The humidity in the morning is usually in the 65 - 75% range and the dehumidifier runs for a few hours and then starts cycling to maintain the set-point. The first week or two you have one it will likely run almost continuously to dry out the furniture, carpet, and clothing. Here in California with the high Electricity prices ($0.20 -$0.25 per kWH), it costs about $25 -$40 dollars a month to operate. In the Summer we have to run the air conditioner too because there is a lot of waste heat from the dehumidifier. There is also an exhaust fan in the bathroom that gets turned on when showering, other than that it isn't used much because it draws in the damp outside air. Since we don't use the kitchen stove much, we also partially sealed the range hood exhaust with Aluminium foil.

Was that a Frigidaire dehumidifier? This Forbes (March 2018) article that rates the best ones lists a Frigidaire machine that removes up to 70 pints:

https://www.forbes.com/sites/forbes-finds/2018/03/05/the-best-dehumidifier/#17a12cf49aea
A possible substitute for the Desonide if you are having a fungal problem is Boric Acid (Sodium Borate Decahydrate, it's sold as Ant and Roach powder in hardware stores). Be sure to get 99% or better purity without any other active ingredients, you don't want insecticide in it. You can sprinkle the powder in shoes, gloves, etc to keep the fungus under control; also in nooks and crannies in the bathroom to kill any mold. I use a concentrated solution in a spray bottle on my feet, and on my fingers as needed. Probably not a good idea to use it on large areas though. Mix some in warm water and shake until no more will dissolve then add water until it does dissolve. It tends to clog the spray nozzle so occassional maintenance is required. Just don't use it on broken skin, in your ears or eyes. Boric Acid is fairly safe, in weaker concentration it used to be the go-to solution for eyewash. (see: https://en.wikipedia.org/wiki/Borax)

Cheers,
Tom
p.s. I just checked the log for the dehumidifier, 229 kWH over 1525 Hours, or 112kWH per month. This place is sealed pretty well though.

In case it wasn't clear, the Desonide cream was for eczema, Tom. Not fungus.

I'll look into Broic Acid, but not sure it sounds like something I'd want to ever use if it's potentially dangerous! lol Appreciate the responses, though!

I realize a dehumidifier + an air purifier will run $300-$400 bucks (not including the replaceable filters and electricity costs). I wish I wasn't so poor! It's not too bad, though, since I'll be starting a summer internship job with pay in two weeks. -Cheers back at you!

Gold Member
2021 Award
Do you reload filters more than 2x a year, phinds?
I replaced the main (HEPA) filter the first time the "replace main filter" light came on. Brand new filter and yet the light didn't go off. Haven't replaced it since but I take it out a couple of times a year to see if it's dirty. The pre-filter takes out pretty much all of the dust and dust is the only think I care about. I clean and or replace the pre-filter a couple of times each winter. I don't use the device in the summer because we keep the windows open. You can buy rolls of pre-filter material cheap and cut to size but of course if allergens are your concern that doesn't help much.

I bought a nice model when I moved into a new house that didn't have central air. I ended up stopping use because I couldn't notice any difference and when I had a window open I felt like I was just filtering the outside world.

kyphysics
I bought a nice model when I moved into a new house that didn't have central air. I ended up stopping use because I couldn't notice any difference and when I had a window open I felt like I was just filtering the outside world.

I think w/ houses, you might need two or three machines, Greg. Even if you move the machine around from room-to-room, the constant opening up of doors and/or windows might be too much for them if the area is very large.

I've heard certain house plants can be very good for removing air toxins naturally, as they absorb them. But, they also increase humidity in a home and then that can be a cause for mold. So, it's a catch 22.

kyphysics
I replaced the main (HEPA) filter the first time the "replace main filter" light came on. Brand new filter and yet the light didn't go off. Haven't replaced it since but I take it out a couple of times a year to see if it's dirty. The pre-filter takes out pretty much all of the dust and dust is the only think I care about. I clean and or replace the pre-filter a couple of times each winter. I don't use the device in the summer because we keep the windows open. You can buy rolls of pre-filter material cheap and cut to size but of course if allergens are your concern that doesn't help much.

Aw, I'd have taken the machine back for a refund! The big box stores, such as a Home Depot, Walmart , etc. are pretty good about it. Although, if you caught it 3+ months later, their policy may not allow it. But, if the light was broken, I might wonder if something else was wrong with the machine. Hmmmm.

But, yeah, I think a main filter replacement even 3x each year isn't too bad. It's probably a total of about $50 or so for a lot of machines I've seen. I also care about dust, in addition to air toxins. It's both for me. Science Advisor Gold Member 2021 Award Aw, I'd have taken the machine back for a refund! The big box stores, such as a Home Depot, Walmart , etc. are pretty good about it. Although, if you caught it 3+ months later, their policy may not allow it. But, if the light was broken, I might wonder if something else was wrong with the machine. Hmmmm. But, yeah, I think a main filter replacement even 3x each year isn't too bad. It's probably a total of about$50 or so for a lot of machines I've seen.

I also care about dust, in addition to air toxins. It's both for me.
Well, again, it does a great job taking the dust out so I don't care about the rest. Also it was more like a year before the light went on.

kyphysics
Gold Member
Was that a Frigidaire dehumidifier?
Yes. Model FAD704DWDA. It's quieter than many others but all electronic controls. Don't count on accuracy of the humidity setting or display, it reads low. For accuracy, I bought a wet-bulb hygrometer from Amazon (less than $15) as the three electronic hygrometers all read differently and the mechanical one is REAL slow to respond. kyphysics Admin I've heard certain house plants can be very good for removing air toxins naturally, as they absorb them. But, they also increase humidity in a home and then that can be a cause for mold. I have a plant in every room. Humidity won't be a problem unless you have a dozen in every room. kyphysics Science Advisor Gold Member$100 for an air purifier, I just paid almost $1000 for a cold-plasma purifier for my house to ensure that all the little critters are killed off (my kid almost died from c-diff earlier this year, so we have justified the expense as a medical necessity). kyphysics$100 for an air purifier, I just paid almost $1000 for a cold-plasma purifier for my house to ensure that all the little critters are killed off (my kid almost died from c-diff earlier this year, so we have justified the expense as a medical necessity). I've never heard of those things you mention above, but I do hope you're family is better and safe now! And, yes,$1,000 is not that much in that context!

kyphysics
Yes. Model FAD704DWDA. It's quieter than many others but all electronic controls. Don't count on accuracy of the humidity setting or display, it reads low. For accuracy, I bought a wet-bulb hygrometer from Amazon (less than $15) as the three electronic hygrometers all read differently and the mechanical one is REAL slow to respond. Ha! Inaccurate purifier humidity detector and an inaccurate replacement light. Wish these companies would get their products right! Appreciate the "wet-bulb hygrometer" tip. I'll look into that too. There's also an "old fashioned feel test." You can Google your city's temp and humidity level that day (assuming Weather.com's humidity ratings are correct). Then see how it "feels" on your skin to be outside vs. inside your home. ...Although, humidity and temperatures change throughout the day. I'd have to double-check to see if the major weather websites are accurate within the hour or not. Science Advisor Homework Helper Gold Member Tip.. instead of buying mould killer sprays for the shower at several £ per bottle we buy cheap unbranded bleach, diluted 50:50 with water in a plant sprayer. Spray regularly even if you don't see any. Ideally just before going to bed so it works over night. Science Advisor Gold Member Tip.. instead of buying mould killer sprays for the shower at several £ per bottle we buy cheap unbranded bleach, diluted 50:50 with water in a plant sprayer. Spray regularly even if you don't see any. Ideally just before going to bed so it works over night. Works fine on tile, grout, glass but attacks most organic materials, like wood, some countertops, paint, etc. I've found a dose of rubbing alcohol kills mold (so does vinegar), and Boric Acid after the alcohol dries keeps mold away. kyphysics kyphysics Tip.. instead of buying mould killer sprays for the shower at several £ per bottle we buy cheap unbranded bleach, diluted 50:50 with water in a plant sprayer. Spray regularly even if you don't see any. Ideally just before going to bed so it works over night. I've heard that bleach being able to kill mold is a myth (at least, a partial one). I initially used a lot of bleach too, but it didn't seem to work. I heard a mold specialist on YouTube talk about how it only kills the surface mold. You need something that goes deeper. White distilled vinegar (which had acid) will actually break it down and kill it totally from what I've read. Not sure if even that is true, but I've seen this "tip" over and over and also mentions of the bleach-mold-myth enough that my go-to now is distilled white vinegar. Feel free to chime in with corrections as anyone sees fit. I want to learn about this subject for long-term knowledge! kyphysics (amazing demonstration) Has anyone heard of or used these non-battery, non-cord, and "all natural" dehumidifiers? These are cheap, mini dehumidifiers that work naturally. No electricity needed until you fill up the beads. Then you have to plug it in for natural air re-release. But it can be used over and over again the same way without running on electricity and can last up to 10 years. Amazon: https://www.amazon.com/dp/B000H0XFCS/?tag=pfamazon01-20 The company is Eva Dry. Pretty good reviews. I could see this being a good investment over a$200 dehumidifier. These are only $15. Granted, I might need to buy 5 of them or so, but they are an interesting alternative! No need to throw away the waste into a landfill either. It's all renewable technology. Science Advisor I might need to buy 5 of them or so You are severely underestimating that amount. This stuff actually nothing more than a big bag of desiccant. Not really comparable to any real dehumidifier. Price- and efficiency-wise you would be better of with buying desiccant in bulk and packing them in socks. I've heard that bleach being able to kill mold is a myth Well, most official mold-killers are bleach-based (but at quadruple price, at least), and that's no myth. Indeed, it is killing only on the surface, and if the reason behind that mold is not addressed then it will grow anew. But that is the same for all mold-killers. Last edited: StoneTemplePython and russ_watters kyphysics You are severely underestimating that amount. This stuff actually nothing more than a big bag of desiccant. Not really comparable to any real dehumidifier. Price- and efficiency-wise you would be better of with buying desiccant in bulk and packing them in socks. Well, most official mold-killers are bleach-based (but at quadruple price, at least), and that's no myth. Indeed, it is killing only on the surface, and if the reason behind that mold is not addressed then it will grow anew. But that is the same for all mold-killers. I was partially thinking the Eva Dry minis might be too small after I posted that message. But, I can see them having some usefulness too, in combination with a compressor dehumidifier. I might look into buying both. Having the Eva Dry mini can be helpful for an isolated "trouble spot" like a bathroom. A regular$200 70-pint type of dehumidifier would be weird to place in a bathroom or even near it. You could also use the mini in a car, an attic, etc. I'm thinking.

***NOTE*** I saw online that silica gel is cancer-causing and there was a warning (thanks to California's Prop 65) on some Eva Dry products (not all) for cancer risks.

re: bleach mold myth

I'll have to look it up again, but from what I recall (I could be wrong), it was only helpful on the top layer of mold. To get all the way "into" it and kill it all off (though not the spores), you can use vinegar, as the acid over time (if left on it) will eat it away. Bleach doesn't seem to get "deep" enough into mold and only kills the top "layer." ...But I'll double-check.

I'll have to look it up again, but from what I recall (I could be wrong), it was only helpful on the top layer of mold.
Just as any other liquid stuff. Borax is a kind of exception since it remains on the surface after drying and so it'll give you a kind of permanent protection, but the price for that is that the surface will be contaminated by that mild poison, of course...
Vinegar - well, we tried that too. Apart from the ineffectiveness the permanent stink was the most noticeable feature...

Again: most official mold-killers are bleach-based (but at quadruple price, at least), and that's no myth.

Gold Member
If you decide to use bleach, add a drop or so of liquid dishwashing detergent to it. That reduces the surface tension of the liquid and allows more intimate contact with the mold.

Rive
Homework Helper
Gold Member
http://blacktoxicmolds.com/bleach-kill-mold.php

Does Bleach Kill Mold
Bleach kills bacteria and viruses and sanitizes the surfaces it's used on. Bleach also kills mold if it comes into contact with it. The spores and allergens from mold are neutralized as well.

Bleach will kill mold growing on non-porous surfaces like glass, tiles, bathtubs and counter tops. However bleach cannot completely kill mold growing in non-porous materials like drywall and wood. Bleach does not penetrate into these non-porous substances and so only the mold growing above the surface is killed.

Explains why it seems to work fine on everything in my shower (stone, sealant and grout which was sealed with stone sealer).

Wouldn't vinegar attack many stone tiles (eg Travertine which I think is limestone like).

Homework Helper
Gold Member
Not sure this is any help to the OP but...

Here in the UK we tends to build well insulated, badly ventilated houses and wonder why they are stuffy. However increasing ventilation can lead to large heating bills in winter. When we built our current house we decided to fit a MHRV (Mechanical Heat-Recovery Ventilation) system. This provides increased levels of ventilation without greatly increased heating bills. It extracts warm humid air from wet rooms like the kitchen and bathroom and expels it via a heat exchanger. Cold air is drawn in from outside and passed through the heat exchanger, which warms it, then it's ducted into bedrooms and living rooms.

We've been impressed by how much healthier our house feels than previous houses we have lived in. In addition we opted for wood, stone and tile floorings rather than carpet. This and the MHRV system seems to help keep dust levels down. We hardly ever have to dust shelves for example.

I have mild asthma and hay fever and both have been much better since moving into this house. If I was ever to build another house I would put this kind of system high up on the wish list.

The down side is that such systems aren't cheap or easy to retrofit to an existing house but it's not impossible.

Gold Member

(amazing demonstration)

Has anyone heard of or used these non-battery, non-cord, and "all natural" dehumidifiers? These are cheap, mini dehumidifiers that work naturally. No electricity needed until you fill up the beads. Then you have to plug it in for natural air re-release. But it can be used over and over again the same way without running on electricity and can last up to 10 years.

Amazon: https://www.amazon.com/dp/B000H0XFCS/?tag=pfamazon01-20

The company is Eva Dry. Pretty good reviews.

I could see this being a good investment over a $200 dehumidifier. These are only$15. Granted, I might need to buy 5 of them or so, but they are an interesting alternative! No need to throw away the waste into a landfill either. It's all renewable technology.

Shouldn't there be a real simple back of the envelope physics / chemistry type of estimate you can do to avoid having erroneous inferences like this?

I liked @Rive's counterpoint, but I also think we're supposed to teach one how to fish, more than give away fish here...
- - - -
a sketch:

pick a rough temperature estimate for your apartment / house. Figure out difference between 'typical' relative humidity and target of 50% of so. Then estimate how many buckets of water would need to be removed each day. It's at least one in my experience in a small apartment. This bucket size is much bigger than the eva dry items. The difference in scale should jump off the page, and tell out at you that the idea can't work.

(Technical Notes: You should be able to do the back of the envelope calculation and estimate this yourself for your circumstances. It gets complicated slightly in that you need to estimate the amount of 'leakage' / 'infiltration' of outside air with moisture into your place. I suppose you could set that up as a differential equation.

A much easier approach is to make use of prior information: a lot of people in a lot of different locations and circumstances have faced this before -- just Google the amount of buckets of water removed in typical apartment of size __ with temp and relative humidity of __ when using a proper dehumidifier...)
- - - -

I was partially thinking the Eva Dry minis might be too small after I posted that message. But, I can see them having some usefulness too, in combination with a compressor dehumidifier. I might look into buying both. Having the Eva Dry mini can be helpful for an isolated "trouble spot" like a bathroom. A regular $200 70-pint type of dehumidifier would be weird to place in a bathroom or even near it. You could also use the mini in a car, an attic, etc. I'm thinking. ***NOTE*** I saw online that silica gel is cancer-causing and there was a warning (thanks to California's Prop 65) on some Eva Dry products (not all) for cancer risks. I also can't imagine putting them in a bathroom... bathrooms have excess moisture by design, due to toilet and shower. By law in CA, I think all full bathrooms have a window or vent (for a reason). Opening a window and putting a box fan in it, will do wonders. - - - - All of that is very straightforward stuff that you should pick up from a little thinking and a mild STEM background. A much harder / more subtle problem, is the cancer risk. I don't know about silica gel in particular, but there's a lot of nonsense that gets tagged as a cancer risk due to prop 65, combined with the innumeracy of judges and activists. Here's a recent, relevant, and extremely thoughtful piece on the matter (topic: Starbucks coffee and cancer) from Bayesian knight, sir David Spiegelhalter: https://medium.com/wintoncentre/coffee-and-cancer-what-starbucks-might-have-argued-2f20aa4a9fed Last edited: ChemAir, Rive and Asymptotic Science Advisor Homework Helper Gold Member I would look up what ventilation rates are recommended by local building codes. The units used are normally ACH or Air Changes per Hour. Typically they recommend several ACH usually more. If your house has higher humidity than outdoors you probably don't have enough ventilation. Asymptotic kyphysics Shouldn't there be a real simple back of the envelope physics / chemistry type of estimate you can do to avoid having erroneous inferences like this? I liked @Rive's counterpoint, but I also think we're supposed to teach one how to fish, more than give away fish here... Note, I speak off-the-top of my head when writing in these threads, so I did think of that problem almost immediately after I posted that message. That's why I acknowledged that earlier when I re:'d him. But, re: teaching to fish. A lot of times it's getting a second/third/etc. opinion on something. I don't say this to mean that you or anyone else (I honestly don't know your intentions) say this phrase in an attempt to humiliate or otherwise put me down, but I know it can feel that way. In other words, it comes off sometimes as rude and presumptuous to say to another person that you don't know how to learn on your own (with the "We should teach you to fish rather than offer you one..." sort of saying). Do keep in mind: a.) Not everyone is as smart as others and can't figure things out for themselves. It can comes off as super offensive when we hear these sorts of admonishments. b.) Often, one might just want a better informed or corroborating opinion. I do that a lot with various things. Similarly, we sometimes just want potentially different or missed viewpoints too. It can be dangerous to just go it alone on things. Asking others (and not assuming a prideful, superman mentality) for help for feedback on something can be extremely important in a lot of areas of life. c.) Sometimes it's about efficiency over self-learning. I agree self-learning is important, but it's not always important. ***The following may or may not apply to what we're talking about here, but I thought I'd throw it in there anyways. One of my favorite mentors, Steven K. Scott, who is a businessman, author, and motivational speaker (he's done billions of dollars in sales and is the record holder in direct sales marketing success in the U.S. with well-known products like The Total Gym and Lori Davis Hair products) talks about the importance of partnering with others and only using your energy to the fullest on things in life that matter most to you in his books. He says a key component to the highest levels of success in life involve "partnering" with others (i.e., working with or learning from) in areas where you're weak. The average person only has two or three (maybe five at most) really great skills that they're better at than most other people (and, hence, use those for their profession). Most people are not-so-good to terrible at most other things in life. If you know you're not good at something and that thing is essential to your success in something you want to accomplish (for which you may be good at another facet of), then you should partner with someone who has those skills. The biggest mistake would be to try to do those things yourself, as that's hobbled and even led to the death of many otherwise good business ideas and companies. The other point about not using all of your energy on everything you do is another important insight. He says if you try your best at everything in life, you'll burn out. That's why he says he sucks at golf and skiing and doesn't care. He does them for fun. If he invested the same effort and energy into those hobbies as he did his primary business, he'd be burned out and unsuccessful (or not as much) in those things that matter (his family and primary career). A lot of people in life can learn a particular skill or figure out some problem on their own, but it's not always the best use of their time/energy/resources. It's much faster and easier to ask others who are more skilled than them. For example, I could learn to change my own oil and fix various problems with my car. But, it may not be worth my time. I've actually learned to do an oil change before, but have forgotten since middle-school (my neighbor showed me how and we did it together on one of his many, many cars - he was a "car nut," who tried to show me lots of things actually). Nowadays, I'd rather just pay for a mechanic to do the work. I don't want to put in the time and energy to learn and do the work myself. I have zero interest in it. Similarly, in other areas of life, many times people just want a quick answer to something. I don't know if this stuff is relevant, but it's what came to mind when thinking of the "Better to teach a man to fish than give him one." maxim. I think that's obviously true for your main profession in life, as you need to be able to problem-solve and show competence in it. But with other things in life, it may not be practical to put a lot of effort into something. Sometimes, you just need to seek a professional and/or it's more efficient to get quick viewpoints from others. Again, I'm not saying that is or isn't applicable here, but just as a general rule of thumb. I'm reminded of Lawrence Krauss' lecture on Richard Feynman's life that I listened to a couple of years ago, in which he said that if Feynman hadn't been so stubborn with trying to figure things out all by himself (and not reading the research of his peers), he'd perhaps have won multiple Nobel prizes and made full on breakthroughs, as opposed to only being on the cusp of those discoveries working alone. I also can't imagine putting them in a bathroom... bathrooms have excess moisture by design, due to toilet and shower. By law in CA, I think all full bathrooms have a window or vent (for a reason). Opening a window and putting a box fan in it, will do wonders. I get a lot of mildew and/or mold in my bathroom window. I think it has something to do with the condensation that forms...It was first window mold/mildew and then a massive mold problem in my bathtub. I used to open the windows a lot for ventilation, but wonder if it also blew in a lot of mold spores (I know all houses have them anyways, but there's a moldy fence nearby and I wonder if that dang thing blows in lots of mold spores into my bathroom. For now, I don't open that window. All of that is very straightforward stuff that you should pick up from a little thinking and a mild STEM background. A much harder / more subtle problem, is the cancer risk. I don't know about silica gel in particular, but there's a lot of nonsense that gets tagged as a cancer risk due to prop 65, combined with the innumeracy of judges and activists. What!? Who said I was STEM? I came here originally as a social science and humanities major to seek HELP from you guys for my math/sci. homework! lol re: cancer warnings - I felt the need to play it safe and not purchase the ones that have the warning. Some Eva Dry products don't have them. The mini doesn't. But they have these disposable pouches (you throw a pouch in a room/location and let the beads fill up and throw the whole pouch away afterwards) that do have the warning. I would consider buying the mini, but not the pouches. Last edited: Tom.G Science Advisor Gold Member Note, I speak off-the-top of my head when writing in these threads, so I did think of that problem almost immediately after I posted that message. That's why I acknowledged that earlier when I re:'d him. But, re: teaching to fish. A lot of times it's getting a second/third/etc. opinion on something. I don't say this to mean that you or anyone else (I honestly don't know your intentions) say this phrase in an attempt to humiliate or otherwise put me down, but I know it can feel that way. In other words, it comes off sometimes as rude and presumptuous to say to another person that you don't know how to learn on your own (with the "We should teach you to fish rather than offer you one..." sort of saying). Do keep in mind: a.) Not everyone is as smart as others and can't figure things out for themselves. It can comes off as super offensive when we hear these sorts of admonishments. It really was meant from a pedagogical perspective, not as an admonishment to anyone, you or otherwise. A lot of people in life can learn a particular skill or figure out some problem on their own, but it's not always the best use of their time/energy/resources. There's a lot of subtleties, but I was strongly hinting at this when I mentioned the role of prior information. My own view is that it may be less about knowing the intricacies of fishing, but instead having a framework for how to think about it. The classic saying involving fishing, not frameworks, is pithier though, I'm afraid. I agree on your car example, but it's still good to have a framework for what goes on with car mechanics so you don't get ripped off. Similar idea with the eva dry. Similar idea in dealing with a lot of things. What!? Who said I was STEM? I came here originally as a social science and humanities major to seek HELP from you guys for my math/sci. homework! lol your handle has "physics" in it -- so I made a guess. There's real value in learning to think this way, again at the framework level. Maybe some motivation to take more STEM courses? re: cancer warnings - I felt the need to play it safe and not purchase the ones that have the warning. Some Eva Dry products don't have them. The mini doesn't. But they have these disposable pouches (you throw a pouch in a room/location and let the beads fill up and throw the whole pouch away afterwards) that do have the warning. I would consider buying the mini, but not the pouches. For what it's worth, I actually purchased a couple of those Eva Drys a while back -- I think the minis for$15. Sometimes for small dollar stuff on Amazon I don't put enough thought in first. They have a hook and are meant to be hung (e.g. in your closet). But if they get bumped and fall onto a hardwood floor they break and spill stupid (cancerous?) beads all over the place.

The framework I mentioned above was more of a post-mortem thought I had a while back on why they didn't do much. It's of course preferable to do a pre-mortem and avoid the whole thing to begin with. But, a second best is to at least do a post-mortem... not something that many people do. I don't think most people do much of either actually.

Asymptotic
NTL2009
... Similarly, in other areas of life, many times people just want a quick answer to something ...
I think what you are missing is that this forum isn't about 'quick answers'. The global guidelines state:
Our mission is to provide a place for people (whether students, professional scientists, or others interested in science) to learn and discuss science as it is currently generally understood and practiced by the professional scientific community.

Asymptotic and StoneTemplePython
Asymptotic
Desiccant breathers for gearboxes operate on a similar principle to the Eva-Dry, but are throw-away and not designed for regeneration. The model I've used was rated for 333 ml of water adsorption using 1.88 pounds (853 grams) of cobalt chloride (moisture indicator) treated silica gel beads. Adsorption depends on temperature and RH, and this manufacturer may have engaged in a bit of apple polishing with their specs insofar as 18% to 23% is the typical maximum water adsorption range by weight for silica gel at 25°C/40% RH.

The $14.97 (USD) Eva-Dry model E-333 specs are for use in an area of up to 333 cubic feet (equivalent to a cube of about 7 feet on each side), with 20 to 30 days (4 to 6 ounces of water adsorption) between regenerations, and an 8 to 10 hour regeneration cycle in a well-ventilated area. Color change is from orange to green which strongly suggests a methyl violet indicator chemistry. The rule of thumb is for an oven temperature of 255°F (124°C) applied for 12 hours to re-generate fully spent gel beads, and gives an idea how hot the Eva-Dry desiccant compartment becomes during regen. Based on the reviews they do a good job removing excessive moisture from small, enclosed areas such as closets and gun safes, but aren't very effective in large open areas. 4 to 6 ounces of water adsorption is about 118 milliliter to 177 milliliters. The aforementioned dehumidifier rated at 70 pints (33122 milliliters) removes about the same amount of water as anywhere from 280 to 187 model E-333 Eva-Dry units. At$14.97 each, this is a purchase cost of about $4200 to$2800 USD.

To put this in perspective, a source of bulk silica gel prices plain, non-indicating 2 to 4 mm beads at about $90 USD, orange (methyl violet based) indicating beads at$140, and blue (cobalt chloride based) indicating beads at $153 per 55 pound drum. StoneTemplePython Asymptotic they break and spill stupid (cancerous?) beads all over the place. I'm not sure about plain silica gel, but the EU recently banned cobalt chloride based (blue-to-pink) indicators regarding cancer concerns, and the gearbox breather manufacturer I'd mentioned previously was beginning a transition to the orange-to-green type. mister mishka i had this very bad mucus cough for months, fearing i would end up with chronic bronchitis i bought an air purifier for 90 euros. it has a coal and hepa filter, uv light and mechanical fan with different speeds (and has NO ionizer). just after a few days, my cough cleared up completely :) kyphysics It really was meant from a pedagogical perspective, not as an admonishment to anyone, you or otherwise. No worries. There's a lot of subtleties, but I was strongly hinting at this when I mentioned the role of prior information. My own view is that it may be less about knowing the intricacies of fishing, but instead having a framework for how to think about it. The classic saying involving fishing, not frameworks, is pithier though, I'm afraid. I agree on your car example, but it's still good to have a framework for what goes on with car mechanics so you don't get ripped off. Similar idea with the eva dry. Similar idea in dealing with a lot of things. That's interesting. I think you're right. You at least want a common sense or basic level of understanding of how the world works, so that you don't get ripped off, as you say, or don't do really dumb stuff. That's the whole point of education: a.) having some knowledge of the world + b.) being able to think critically/logically so as to solve at least some simple everyday life problems. Some basic literacy in physics, biology, history, politics, etc. is needed for human survival if nothing else. I guess someone can debate about where to draw the line in terms of energy/time spent on learning various things, but I agree with the basic premise above. your handle has "physics" in it -- so I made a guess. There's real value in learning to think this way, again at the framework level. Maybe some motivation to take more STEM courses? Heh. I'd love to in an ideal world man! I actually just wrote not too long ago in another thread (about fast growing future jobs) that I think in some world where all of one's basic survival needs are met, maybe we'd see people pursuing those "useless" degrees (philosophy, art history, gender studies, etc.) more. I've always felt "useless" was a relative term and we simply live in a world where meeting our basic human needs (food/clothing/shelter/health care) still requires a lot of work and takes up the majority of most people's time. Most people wake up and work 9+ hours a day. Not much time in their free time to do anything else. E.g., it took me two weeks to learn the nuances of doing my taxes (first time self-preparer) this year and that was during my free time. In a possible futuristic world, where one didn't have to worry about food and the basics of life, maybe we'd all focus more of our energies on these intellectual topics. I try to learn about other subjects while driving and working out. I listen to podcasts of subjects of every background. And I enjoy discussing various ideas in a place like this. re: screen name I do that with lots of sites for easy screen name recollection. I'll put some aspect of the site's title into my screen name. Some people just use the exact same sn across sites. That's another way to do it. For what it's worth, I actually purchased a couple of those Eva Drys a while back -- I think the minis for$15. Sometimes for small dollar stuff on Amazon I don't put enough thought in first. They have a hook and are meant to be hung (e.g. in your closet). But if they get bumped and fall onto a hardwood floor they break and spill stupid (cancerous?) beads all over the place.

The framework I mentioned above was more of a post-mortem thought I had a while back on why they didn't do much. It's of course preferable to do a pre-mortem and avoid the whole thing to begin with. But, a second best is to at least do a post-mortem... not something that many people do. I don't think most people do much of either actually.

Cancerous beads - no thanks! Yeah, I think I'll avoid those.

Agree that we should do a post-purchases analysis of things! It's tempting when you see a \$15.00 item to just get it. I appreciate everyone's feedback on these various items, as it's given me some useful things to consider!

kyphysics
I think what you are missing is that this forum isn't about 'quick answers'. The global guidelines state:

Does that apply to "General Chat," though? I figured this was more relaxed and not like the homework help section, where we had to show proof of working out a problem first before asking for help.

http://blacktoxicmolds.com/bleach-kill-mold.php

Explains why it seems to work fine on everything in my shower (stone, sealant and grout which was sealed with stone sealer).

Wouldn't vinegar attack many stone tiles (eg Travertine which I think is limestone like).

Here is what I came across, CWatters (see link and quoted text below):

https://www.servicemasterrestore.com/blog/mold-damage/mold-myths-will-vinegar-kill-mold/

Does Bleach Kill Mold?
The idea that bleach can kill mold is a myth! In reality, bleach only kills surface mold, not the membrane that lives underneath the black, fuzzy growth. This mold membrane is where the heart of the problem truly lies. If you try using bleach to kill mold, it will usually return with a vengeance. The chemical structure of bleach makes it unable to penetrate porous surfaces like drywall or wood, which means that mold membranes will simply retreat deeper into whatever surface they're on to avoid the chemical. Once first exposed to bleach, the mold recognizes it as a threat and can actually use it as a fungal food to grow more rapidly. That's right – using bleach to kill mold can actually feed the problem! The Environmental Protection Agency (EPA) does not recommend using bleach to kill or remove mold, except under special conditions when supervised by a professional. If you want to effectively eradicate mold in your home, bleach simply won't cut it.

Does Vinegar Kill Mold?
Just because bleach is out doesn't mean you don't already have something in your pantry that can effectively kill mold. That old bottle of vinegar in your cupboard is actually a powerful tool. White vinegar is a mild acid that is known to kill roughly 82 percent of mold species, and it can even help prevent mold outbreaks in the future. Use vinegar to eradicate small outbreaks of mold by following these simple steps:

1. Make sure you are wearing protective gear, including a mask, goggles and gloves, to protect yourself from direct exposure to mold.
2. Pour plain, white distilled vinegar into a spray bottle. Because mold is such a resilient force, it's best not to dilute the vinegar.
3. Spray the vinegar directly onto the mold, and let it sit for at least an hour without rinsing or scrubbing so that the vinegar gets completely absorbed by the mold.
4. If scrubbing is necessary, make a baking soda solution to use after the vinegar. Combine 1 teaspoon of baking soda with 2 cups of water in a spray bottle and shake until thoroughly mixed.
5. Spray the baking soda solution directly onto the mold and vigorously scrub the area with a scrubbing brush or scouring pad. Safety tip: be sure to use protective gear while scrubbing to prevent direct contact with the mold.
6. Rinse the area with clean, warm water.
7. Spray the area again with either the vinegar or the baking soda solution and let the chemicals dry naturally to help kill any remaining mold and prevent regrowth. The strong smell of vinegar will naturally fade within a few hours.

1. Also, here is the EPA mold link from that website piece:
https://www.epa.gov/mold

There's a whole page/section from the EPA dedicated to mold. I've seen a few other websites say that bleach killing mold is a myth as well and also the recommendation of vinegar. Not sure how true the vinegar recommendation is! Trying to find out!

EDIT: I see your quote post actually distinguishes between porous and non-porous surfaces now, CWatters. So, my post was maybe irrelevant. But, it's still good to know perhaps for other people wondering about this topic.

EDIT 2: I'm also not sure why there is a random "1." above. It keeps appearing in my post no matter how many times I've tried to delete it. Weird.

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