Alk not tracking as expected

Amoo · Jul 19, 2015

~150G water volume

Thursday:
T - 79.5, SG - 1.024, pH - 8.09, Ca - 475ppm, Alk 7.73dKH, Mg 1040ppm
Dosed - 1250ml 2 part DIY Mg Mix (5 parts CL to 3 parts Sulf) and 12ml DIY Nopox

Friday:
T - 79.5, pH - 8.09, Mg 1200
Dosed 1000ml 2 part DIY Mg Mix and 12ml DIY Nopox

Saturday:
Dosed 12ml DIY Nopox

Sunday:
T - 79.6, SG - 1.025, pH - 8.06, Ca - 415ppm, Alk - 7.84dKH, Mg 1420Mg
Dosed 12ml DIY Nopox

The Mg Dosing was due to a IO bucket that mixed up at 880ppm Mg (double checked with 2 seperate Red Sea Tests). The DIY Nopox dosing is to combat some Nitrate and Phosphate.

Ca and Mg are always measured with Red Sea Kit. Alk with Hanna. I'm confused how I could drop 60ppm Ca and go up .1dKH in alkalinity? FWIW I added about 30lbs of new rocks abotu a month ago that are still building Coralline.

Randy Holmes-Farley · Jul 19, 2015

I expect the calcium measurements were off (before or after or both) if you were not dosing either calcium or alkalinity.

Amoo · Jul 19, 2015

Nope, no 2 part yet as my system hasn't started demanding it. I'll test again in a few days and see where things land, but I would have expected some alk consumption over a 3-4 day period. I realize the increase is possibly just measurement tolerance.

Randy Holmes-Farley · Jul 19, 2015

FWIW, there's no way for calcium to rise or fall on its own in a case like this.

Amoo · Jul 19, 2015

That was my thought as well, thanks Randy. Just wanted to make sure that absolutely nothing in either of my DIY mixtures was somehow converting into alk or binding the Ca. We'll chalk this one up to operator error. Maybe I need a backup Ca test since I have a backup Mg and Alk.