Alkalinity/Calcium Balance Issues

optimisticdingo · Feb 2, 2021

Hey guys! I'm still new to this reefing hobby and I'm encountering an issue with keeping my Alkalinity and Calcium balanced. Every time I test pH it's around 7.9 to 8 but for the past few weeks my calcium has been reading rather low (200-300 ppm) but my kH has been at 14. I've recently done a 20% water change and the kH has stayed the same. What should I do to lower the kH and help keep my kH and Calcium balanced. I've read that high kH can cause calcium to deplete and vice versa. Any help that you can give would be greatly appreciated.

blasterman · Feb 2, 2021

I would suspect your test kits. Either the salt mix is bad, which is possible but rather rare, or you are testing wrong. In the grand scheme of probabilities its a testing issue.

Over dosing kalk can cause a calcium fallout and high alk, but your tank would be coated in white powder.

optimisticdingo · Feb 2, 2021

blasterman said:
I would suspect your test kits. Either the salt mix is bad, which is possible but rather rare, or you are testing wrong. In the grand scheme of probabilities its a testing issue.

Over dosing kalk can cause a calcium fallout and high alk, but your tank would be coated in white powder.

I'm just using a standard API test kit for both. Do you have any recommendations for other test kits?

tundraguy1106 · Feb 3, 2021

optimisticdingo said:
I'm just using a standard API test kit for both. Do you have any recommendations for other test kits?

Hanna or NYOS for Alk (keep in mind the results though consistent will be different from each other if you have both). Calcium I like salifert or Red Sea. Hanna is complicated as well as very sensitive to different things.

Randy Holmes-Farley · Feb 3, 2021

I agree that 200-300 ppm calcium is likely test error, not a real result.

It would be hard to attain even intentionally by adding lots and lots of alkalinity additives and no added calcium.