How Much Calcium Carbonate to Add for Optimal pH in a Fish Tank?

In summary, the conversation discusses the need for a fish breeder to adjust the water's pH from 5.0 to 6.5 using only calcium carbonate. The calculation for the amount of calcium carbonate needed is complicated due to the presence of other buffers and the type of neutralization required.
  • #1
marcelo
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Considering a fish breeder decided to breed small fishes which needs a pH between 6,0 to 7,0 to stay alive. He needs to adjust the water's pH that is 5,0 to a value of 6.5, having available only calcium carbonate. The mass in mg added to 5L of water is about:
A)2,5

B)5,5

C)6,5

D)7,5

E)9,5
 
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  • #2
What do YOU think?
 
  • #3
I think if I have 10-5 of pH value we need 10-9 of pOH value to make Kw=-14
the reaction of water with CaCo3 is 2 per 1
(H+) + (OH-) + CO3(2-) + Ca(2+)----> HCO3(-) + Ca2(+) OH(-)
(H+) + (OH-) +HCO3(-) + (Ca(2+) + OH(-)-----> H2CO3 + Ca(OH)2
since I need only 10^-2 concentration of OH- and we have only 5L of water:

5.10(-2) mols of OH-. But 1 mol of CaCO3 gives 2 mols OH, we need only 2.5x10(-2) but this answer is wrong,
 
  • #4
As asked this question has no answer, as we don't know what is responsible for the initial pH - typically water contains some buffers and the amount of base/acid required to change the pH depends of their concentration. Then, adding carbonates creates another buffer set, making the calculation a bit more convoluted than just the neutralization would do.

marcelo said:
I think if I have 10-5 of pH value we need 10-9 of pOH value to make Kw=-14
This is way too cryptic for me to guess what you mean. Or, if I guess right, you are mixing pH with [H+] and so on as if they were the same thing - they are not.
 
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1. What is the ideal pH level for a fish tank?

The ideal pH level for a fish tank varies depending on the type of fish you have. Generally, a pH level between 6.5 and 7.5 is considered safe for most freshwater fish.

2. How does the pH level affect fish in a tank?

The pH level of the water in a fish tank is crucial for the health and well-being of the fish. A pH level that is too high or too low can cause stress, illness, and even death for the fish. It can also impact the growth of beneficial bacteria and the effectiveness of water treatments.

3. What causes pH levels to change in a fish tank?

There are several factors that can cause pH levels to change in a fish tank. These include the addition of new fish, overfeeding, decaying organic matter, and the use of certain types of water treatments. Water source and tank maintenance can also play a role in pH fluctuations.

4. How can I test the pH level of my fish tank?

You can test the pH level of your fish tank using a pH testing kit. These kits typically come with test strips or liquid solutions that change color based on the pH level of the water. It is important to test the pH level regularly and make adjustments as needed to maintain a safe and stable environment for your fish.

5. How can I lower or raise the pH level in my fish tank?

To lower the pH level in your fish tank, you can use natural methods such as adding driftwood, peat moss, or almond leaves. You can also use commercial products specifically designed to lower pH levels. To raise the pH level, you can use crushed coral, limestone, or baking soda. It is important to make gradual changes and monitor the pH level closely to avoid shocking the fish.

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