Detritous and Alkalinity

reefer1 · Jun 20, 2015

Hi,
The last few times I stirred up the detritous that had settled in the overflow and sump or stirred my sandbed, I noticed the alkalinity moved up several points (5-8ppm).
Does this make sense?
Thanks

Randy Holmes-Farley · Jun 20, 2015

There are a couple of possibilities, plus the potential for coincidence for that pretty small rise.

If there were any solids still suspended in the water (even if too small to readily see), that could raise the alk detected with a titration test since and solid calcium carbonate will dissolve in the test and most random organic matter will show some uptake of acid in that procedure.

If you stirred up sand deep enough that the pH was lower there, it may have had extra dissolved calcium carbonate in it, resulting in a small addition to the tank alkalinity.

All things considered, I'd put coincidence as the most likely.