Does activated carbon remove dosed phosphate?

miller75 · Nov 23, 2022

I have a Red Sea Reefer 425XL and I am really struggling with my phosphates, I just cant get them up. I only have 2 small hammer frags and 2 small torch frags

I have been dosing Nyos Phosphate + and they will not go up and stay up, yesterday I checked them and they were 0.003 ppm (1 ppb) using Hanna ULR Phosphorous checker so I added 25m/l of the Phosphate + which should have brought them up to about 0.06 ppm.

Tonight when I tested them they were 0.006 ppm (2 ppb) so I added 40 m/l (Should have brought it to 0.1 ppm), waited about 3 hours and tested again, I get 0.04 ppm (13 ppb).

This has been going on for about 6 months now and I just cant get them to stay up, I have been thinking about what could be pulling them out, the only filtration I have is a Nyos 120 shimmer, and Clarisea roller mat and a reactor with Red Sea activated carbon.

Could the activated carbon be pulling the liquid phosphate out?

Miami Reef · Nov 23, 2022

No, activated carbon has little to no effect on phosphate, however, calcium carbonate rocks and sand can bind a substantial amount of phosphate until it reaches a higher equilibrium.

Dose more aggressively.

Randy Holmes-Farley · Nov 23, 2022

No, activated carbon will not bind appreciable phosphate from seawater.

Exposed calcium carbonate surfaces on rock and sand bind a lot, however, so dosing often requires far more than "expected".