High Alk Low Calcium

425nm · Jan 15, 2015

Tested one of the work tanks today to discover that the alk is off the charts. My salifert kit is telling me its over 15dKH and my calcium is at 204ppm.
I dose for alk with soda ash and calcium is done with the Seachem dry powder.

All the livestock appears to be fine. Nothings even browned out or closed up.

How do I go about fixing this? Let the alk drop to a more reasonable level on its own. Should I try to bump the calcium up on its own? Or will it just precipitate on me with the alk being so high?

Randy Holmes-Farley · Jan 15, 2015

How did you get where you are? Were you not monitoring calcium for a VERY long time while you added a lot of alkalinity? Did you add excessive amounts of alkalinity?

If that isn't true, then the low calcium is likely testing error. Don't boost it to 400+ ppm until you verify that the value really is that low. It really cannot normally get that low as corals won't even be able to take it up properly.

Try using both kits on some new salt water first.

425nm · Jan 15, 2015

I'm not entirely sure. Usually I'm the one dosing the tank. One of my coworkers or a volunteer may have over done it without realizing.

A month ago the alk was 8.4 and the calcium was 400ppm.
I've triple checked my tests and had my coworker do them ad well.
So do I just not dose anything until the alk drops? Do small water changes daily to bring it down?

Crazy Corals · Jan 15, 2015

I would do the small water changes do you have corals in tank

scardall · Jan 15, 2015

Take water to a LFS and test it for Magnesium,alk and Calcium.

425nm · Jan 15, 2015

I do have corals in the tank and none of them appear stressed. Polyps are out, and colour is normal.

I'm going to grab my kits from home to double check. It'll be faster than going to the LFS.

Randy Holmes-Farley · Jan 15, 2015

I expect the 200 ppm calcium is in error.

If the alk is right, just don't dose anything while waiting for it to drop. If it is not dropping fast enough for you, water changes can help a little (but not much). Even a 50% change with 11 dKH new salt water (if that is what you use) only drops the alk to 13 dKH.