New "Cured" dry rock causing Alk Drop?

ihavecrabs · Feb 10, 2016

So this weekend I plumbed my 120 (new) into my existing 60g Shallow. Before turning on the plumbing between the two tanks to begin mixing the water, I tested and corrected the new 120 to match the existing 60 in Alk, Ca, and Mg. (8.12, 410, 1500 respectively)

Mixing started Saturday and on Monday I test Alk and it has dropped to 7.28 from 8.12 in two days! Previous to mixing the two systems, my alk was extremely stable moving between 8.12 and 8.28

Could it be all the new cured dry rock that is sucking up the Alk?

Thanks for your input!

ihavecrabs · Feb 10, 2016

@Randy Holmes-Farley

Randy Holmes-Farley · Feb 10, 2016

Fresh calcium carbonate surface can bind some ions from solution, including magnesium and carbonate, so that may be the explanation. That effect is short lived, so it is not an ongoing issue.

However, other changes might impact demand in the tank, such as changes in pH.

ihavecrabs · Feb 10, 2016

Thanks Randy.

I will continue daily/twice daily monitoring until I determine it is stable again.

As far as PH goes, it has remained stable throughout the process (monitored by the Apex Lab). Only difference is the pH during the main tanks night is now coming in at its lowest point as 8.06 instead of 8.01 as my previous tank was only 20g frag on the opposite light schedule.