Phosphate

[splunty]

Sounds likely. Rocks and sand will only bind up to a certain amount that is related to the concentration you are trying to keep in the water. They bind a ton more at 1 ppm than at 0.02 ppm, but at any concentration, there is a fixed amount that will bind, and you probably reached it.

Good morning, Randy.

I had a similar thread to this one a few weeks ago. Looking back at my numbers after I finally got phosphates stable, I became pretty convinced that my phosphate instability was caused by pH instability. It's far from scientific, but my perceived pH results (Salifert) were near-linear with my phosphate readings.

When I had been struggling to keep pH above 8, my Phosphates were fine. Over the course of a week or so after switching to b-ionic my pH rose to 8.3-ish (again, Salifert). It was in that window that my Phosphates bottomed out.

After a few days of dosing (and pH staying as stable as I could tell with that test), Phosphates stabilized and I've been .07 to .10 since then.

Am I crazy? Or is there actually a link between pH and phosphates, or at least the ability of the Salifert test to present results?