Planted Tank Guru
Join Date: Jan 2010
Location: Contra Costa CA
Test the GH and KH.
I know many of the ADA substrates remove the carbonates, and this allows the pH to drop.
Add carbonates, and this will keep the pH up.
I do not know if they remove the minerals we measure as GH- calcium and magnesium.
I would use a 2-part correction.
1) When doing water changes, make sure the new water has plenty of carbonates, and is the right pH. You may need to add potassium bicarbonate or Sodium Bicarbonate (Baking soda) to raise the KH. If the substrate is also removing the minerals such as Ca and Mg, then correct these, too, with something like Seachem Equilibrium, or perhaps a specialty shrimp mineral supplement (I do not know much about these- do some research)
2) Add something to the filter. Any of these materials will dissolve and add minerals and carbonates to the water.
Limestone sand or fine gravel, Coral sand, Oyster shell grit, Dolomite and similar materials have both carbonate and the minerals calcium and magnesium.
If your GH is already OK, and the substrate is not removing these minerals, then maybe you do not want to use these materials. Depends on what sort of range of GH your livestock can handle.
By adding these to the filter in a nylon stocking you can remove them if they are not working out.
They will dissolve more in low pH water, and less as the pH rises. It is a matter of equilibrium. The less minerals in the water (removed by the substrate) the more these materials will give to the water. The reaction is slow, so it is not to be depended on when you are doing a water change with too-soft water. If the water starts off good, then these materials can help keep it OK.