PO4. If your nitrates are low to 0 then it has to be PO4. Cheato likes high phosphates. Red slim remover if you must but follow the instructions very closely. Phosbuster works very well if you can get some, to reduce the high phosphates to much lower levels, then rowa and a phosban reactor to manage the lower levels.
When you get your test kit take your water sample from a very low flow area, like a cave and the results will be much closer to reality.
Good luck. It can be a very frustrating battle and about the time your ready to give up it will go away.
Scott
|