Low Alk in QT

SeeFu · Oct 26, 2020

I've got a 20 gal QT with about 15-20 frags in it. Every night i do a 1/3 gal water change from my DT to the QT. My DT has consistently meassured around 9.5 dkh. After weeks of loosing frags I finally decided to test the QT it showed a Alk of 5.38. Is that even possible to get that low? I rechecked the Alk and i got a similiar reading. The tester I was using is the hanna checker and on my DT the Hanna and trident measure very close. My calcium and magnesium levels were fairly normal though, 450ish for calcium and 1425 for magnesium. Any idea's what's happening? On the QT I don't do anything, not even kalkwasser. I figured if my DT is reading fine and i'm doing more than a 10% water change every week i should be fine.

Randy Holmes-Farley · Oct 26, 2020

SeeFu said:
I've got a 20 gal QT with about 15-20 frags in it. Every night i do a 1/3 gal water change from my DT to the QT. My DT has consistently meassured around 9.5 dkh. After weeks of loosing frags I finally decided to test the QT it showed a Alk of 5.38. Is that even possible to get that low? I rechecked the Alk and i got a similiar reading. The tester I was using is the hanna checker and on my DT the Hanna and trident measure very close. My calcium and magnesium levels were fairly normal though, 450ish for calcium and 1425 for magnesium. Any idea's what's happening? On the QT I don't do anything, not even kalkwasser. I figured if my DT is reading fine and i'm doing more than a 10% water change every week i should be fine.

Certainly it is possible, and you are adding only a very tiny bit of alk with that water change (less than 0.1 dKH per day). Dosing is advised.