Where's my Magnesium going?

[cubera]

If your Calcium is holding steady and your tank is happy don't worry about it. Mg++ is one of those numerous trace elements in natural sea water that is very hard to pin down without expensive laboratory analysis.

[Instar]

Your Alkalinity is way too high for that calcium, providing that your tests are accurate. All that extra carbonate is combining with your Mg and salting it out. It'll probably come back up as Mg comes back into solution when the alkalinity comes down in balance with the calcium, if you can accomplish that. Whatever changes are made to alkalinity, do it very, very slowly. If you are having difficulty with some species, that high of an alkalinity vs the calcium not high, might explain it.

[Jimnorris]

Just a thought---would it be better to bring the alk down?
Jim

[Jimnorris]

Joshua I keep mine at 10 to 11. And my calcium is at abiut 430. But I have also been reading that higher alk helps the color and growth of sps corals??? My thought is at 415 your calcium is good! Now I keep my magn on the high side 1500. Is it just as easy to raise the calcium as compare to lowering the alk? And how does this affect the magn level?
Jim