Kalkwasser can be a great balanced additive when used properly if
needed. For an FOWLR
tank, unless the CaCO3
demand is heavy you will probabley not need any additives. Regular weekly water changes should provide all you need as long as the saltmix being used is balanced.
Nothing should be added until you can determine what the levels are through testing with a proper kit for both alkalinity and calcium. Once done, then you can detrmine whether the water changes will keep up or if suppliments may be needed. You will need to do a few tests over a weeks period or so to map the rate of depletion for both alk
If the numbers fall short, a two part balanced liquid additive or kalk
can then be used to augment the shortfall. Imbalances are best corrected by either a good marine buffer for alk
and a CaCl
additive for calcium.