Does Raising CA Lower Alk.

ddrueckh · Feb 15, 2016

I raised my CA from 390 to 440. I tested two days later and noticed my Alk dropped from 8.46 to 6.66. I checked twice with my Hanna checker and one with Red Sea. My Mag is 1400. What happened? Thanks.

Randy Holmes-Farley · Feb 15, 2016

ddrueckh said:
I raised my CA from 390 to 440. I tested two days later and noticed my Alk dropped from 8.46 to 6.66. I checked twice with my Hanna checker and one with Red Sea. My Mag is 1400. What happened? Thanks.

Alkalinity is depleted in most reef tanks, and your drop is less than 1 dKH per day, which is even on the low end of depletion rates.

So I suggest looking into regular dosing of calcium and alkalinity.

Randy Holmes-Farley · Feb 15, 2016

Randy Holmes-Farley said:
Alkalinity is depleted in most reef tanks, and your drop is less than 1 dKH per day, which is even on the low end of depletion rates.

So I suggest looking into regular dosing of calcium and alkalinity.

I do not think that specific calcium addition played an important role in the alk drop.

This has more on the methods available to supplement:

http://www.reefedition.com/the-many-methods-for-supplementing-calcium-and-alkalinity/

ddrueckh · Feb 15, 2016

Randy. Thanks for the reply. I am already dosing CA and Alk. I dose 45ml each of your two part and also top off with kalk (1/2-1 gallon per day).

ddrueckh · Feb 15, 2016

The tank is a mix of sps and lps.

Randy Holmes-Farley · Feb 15, 2016

Ok, I'd just look to dose a bit more. :

Maybe the upped calcium is encouraging some coral growth, or more abiotic precipitation of calcium carbonate, but it may just be more growth unrelated to the dosing.

ddrueckh · Feb 15, 2016

Okay. If one has precipitation, do both ca and Alk lower?

Randy Holmes-Farley · Feb 15, 2016

Yes. Whether a coral uses it or it is precitation, alk and calcium are used together, about 18-20 ppm calcium for each 1 meq/l (2.8 dKH) of alkalinity.