How Much 45% Phosphoric Acid is Needed to Raise PO4 by 1ppm in 1 Litre of Water?

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Discussion Overview

The discussion revolves around calculating the amount of 45% phosphoric acid needed to raise phosphate (PO4) levels by 1 ppm in a specified volume of water, specifically in the context of maintaining a safe environment for fish. Participants explore various methods and calculations related to this chemical application.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant asks how much 45% phosphoric acid is needed to raise PO4 by 1 ppm in 1 liter of water, emphasizing the importance of accuracy due to the involvement of fish.
  • Another participant suggests a rough calculation method involving the dilution factor of phosphoric acid and its molecular weight to determine the required volume.
  • One participant calculates that approximately 7.2 ml of 45% phosphoric acid would be needed to raise PO4 by 1 ppm in 300 liters, but later expresses doubt about this estimate.
  • A different participant proposes a method using the concentration and volume relationship (conc1 x vol1 = conc2 x vol2) to derive the necessary amount of acid.
  • Another participant provides a calculation based on a hypothetical scenario of 100% phosphoric acid, concluding that 0.67 ml would be more accurate for the 300 liters.
  • One participant mentions the phosphoric acid content in a can of cola and suggests a safe way to add it to a drink, which raises questions about the relevance of this example to the original query.

Areas of Agreement / Disagreement

There is no consensus on the exact amount of phosphoric acid needed, as participants present differing calculations and methods, leading to uncertainty about the correct volume required.

Contextual Notes

Participants express varying assumptions regarding the concentration and volume calculations, and there are unresolved discrepancies in the estimates provided. The discussion also shifts between different contexts (fish tank vs. soda), which may affect the clarity of the calculations.

skyshrimp
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How much 45% phosphoric acid (in ml) would it take to raise PO4 by 1ppm in 1 litre of water?

I need to be sure as fish are involved. It will be administered over a 24 hour period.
 
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Without a lot of thinking (maybe):

1 ppm of phosphoric acid (measured as a fluid in mls) in a liter would be 1/1000 mls.
45% phosphoric acid would require 1/45 x 1/1000 mls.
Figure out the fraction of the PO4 in the phosphoric acid by its molecular weight.
Multiply by that number to get your result.
 
Thanks,

I calculate that at about 7.2ml of 45% phosphoric acid to raise PO4 by 1ppm in 300 litres.
 
Add slowly or high local concentrations may cause problems before it is mixed throughout the whole volume.
 
skyshrimp said:
I calculate that at about 7.2ml of 45% phosphoric acid to raise PO4 by 1ppm in 300 litres
Are you sure seems high to me?
 
gleem said:
Are you sure seems high to me?
That's was my first thought, but
skyshrimp said:
in 300 litres.
so 300x of a liter's worth.
 
my method is conc1 x vol1 = conc2 x vol2
 
Let’s say you had it at 100% then 1ml would be enough for 1M ml =1000liters
Therefore at 45% 1 ml would be enough for 450 liters
You have 300 liters, so 2/3 of that.
Solution:
Get a cup of water add 1ml and mix
Drop 1/3 of a cup of the mix
Add the remaining mix to your water. Problem solved!
You need .67 ml of it but that’s harder to calculate
 
  • #10
Thanks,

I made a mistake with my rough calculation. I should have estimated 0.72ml, not 7.2ml. 0.67ml is more accurate. I was adding slowly and testing each day. I got to 1ppm quickly, so knew my math was off.
 
Last edited:
  • #11
Also, there is 60mg of phosphoric acid in a can of Cola-Cola.

One drop of liquid is 0.05ml which is 50mg. My phosphoric acid is 45%, so I figure I can add 2 drops to a 330ml drink to safely give it some extra bite.
 
  • #12
skyshrimp said:
I need to be sure as fish are involved.
skyshrimp said:
Also, there is 60mg of phosphoric acid in a can of Cola-Cola.

One drop of liquid is 0.05ml which is 50mg. My phosphoric acid is 45%, so I figure I can add 2 drops to a 330ml drink to safely give it some extra bite.
Wait, you've gone from a 300 liter fish tank to a can of soda? I'm getting dizzy... o0)
 

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