PO4 was 0.25 and NO3 was 20 last week so I ran GFO in a reactor for a few days then removed it and it dropped the PO4 to 0.0 measured with a Nyos test kit. Yesterday after a 18% water change the PO4 is still 0.0 and NO3 is 12. Ive been trying to increase feedings to twice a day bump up the phosphate.