Phosphate reduction not working.

backbayreef · 2026-11-15T14:30:33-0500

James CNM said:
Yep carbon dosing, dissolved in kalk to reduce no3. Was 20, It has taking time, i have also noticed a reduction in po4. I used to clean the glass twice per week, its now over a week when i see a slight film on the glass, po4 sits 0.003 Hanna, no3 is around 10 (salifert).

Just want to be clear and set the record straight (for others that come along later). Given the OP’s NO3 of 3.8ppm and PO4 of 0.69ppm, your recommendation is to dose more carbon source to reduce PO4?

James CNM · 2026-11-15T14:36:25-0500

backbayreef said:
Just want to be clear and set the record straight (for others that come along later). Given the OP’s NO3 of 3.8ppm and PO4 of 0.69ppm, your recommendation is to dose more carbon source to reduce PO4?

I don't recall giving a recommendation

I said what has worked for me. Depends on the test kit. I disclosed what tests i use

James CNM · 2026-11-15T14:56:21-0500

exnisstech said:
IME my tanks that run high PO4 require a continuous maintenance program to keep them from continuing to rise. I have one tank that's been running for over two years with PO4 that I really don't know how high it actually gets because I can't measure higher than 0.9 using my Hanna ULR tester. I'll run some GFO and get it down to around 0.5 and it will creep back up to 0.9+ and I'll change out the GFO and repeat. It's never been below 0.3. Tank doesn't look as nice as yours but it's algae free so I don't fret it.