High Alk Low Cal

[Mark’sReef]

Hello all I am having some trouble with my Kh being a little high and cal/mag being a little bit low. About a week ago I went to test my water at LFS because my corals were doing horrible and my kh was through the roof around 330 alk. I have done a series of water changes to get my tank back to its normal kh of 12 but would like to lower it to around 8 or 9. I would also like to slightly raise all my other parameters so all suggestions are welcomed.
PH 8.0
Kh 12
Calcium 320
Magnesium 1300

 

[jda]

Dp you mean 12 dKh of alk and 330 of calcium?

If so, you can lower alk in your fresh salt mix using an acid or wait for it to be used by a coral, algae or other organism.

For calcium, you can use many supplement to raise it. The cheapest and easiest might be Calcium Chloride which you can get from amazon or in many ice melt products.

Magnesium Chloride, also a ice melt product, or Epsom Salt can raise magnesium.

There are calculators online with how much to add... but this one works:
https://reef.diesyst.com/chemcalc/chemcalc.html

 

[CasperOe]

As for your alkalinity, sitting at 12 is not desperately high. You could just wait it out; your tank will consume it but by bit. If you don't replace it, it will drop. If you want it to drop faster, simply do another water change.

Depending on which salt mix you're using, that will do the job.

As for the calcium, dose it back up to where you want it to be. Slowly!