Randy Holmes-Farley
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My Tank Thread
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Randy - thanks for the explanation! How do you deal with the rising calcium? Just use alkalinity replacement and wait for the calcium to naturally drop, rely on partial water changes to maintain an equilibrium, or something else?
I changes 1% daily with a lower calcium mix, normal Instant Ocean. Here's my comment after a Triton test:
http://www.reefedition.com/my-triton-testing-results-by-randy-holmes-farley/
Calcium (Ca). In my reef aquarium, I use only Instant Ocean salt and I have not added any additional calcium except as limewater for a number of years (during which time I have continued regular 1% daily water changes). So why is my calcium level (472 mg/L) higher than one would normally expect for Instant Ocean (maybe between 350 and 400 mg/L)? That long term rise in calcium is actually the expected result when using limewater to maintain alkalinity.
Limewater adds calcium and alkalinity in exactly the same proportions as in pure calcium carbonate. So if that is what is used by corals to make skeletons, and what precipitates on pumps and such, then calcium would stay constant.
But both magnesium and strontium get into growing calcium carbonate crystals in place of some of the calcium. A few percent of the calcium is replaced this way. Consequently, since the same amount of alkalinity (the carbonate) is used over time, and somewhat less than the balancing amount of calcium, calcium rises if alkalinity is maintained. I’m happy to see the result match the theory, and the calcium level seems fine to me.