Can't keep the PO4 down. Running GFO for months.

[paragrouper]

Are you using a Hannah “Phosphorus ULR?” That is the one that reads in parts per billion. The phosphate ULR reads in parts per million.

 

[Zoa.Mania]

Hello everyone I retested with another checker (ULR) and we got 71ppb. I retested with mine with the same cuvette making sure we did it on the same glass cuvette and got 74ppb. Very very light blue almost unrecognizable compared to a few months back when it was dark royal blue.

74ppb = 0.074ppm

This is within acceptable range. You’re good
Don’t do anything just keep it under 0.1 ppm and you’ll be alright

Good luck

 

[paragrouper]

Are you using a Hannah “Phosphorus ULR?” That is the one that reads in parts per billion. The phosphate ULR reads in parts per million.

The reason this is important, there is a conversion you must do from phosphorus to phosphate. In your case 74ppb (phosphorus) would convert to 0.218 ppm (phosphate). The link below is to a handy conversion table from Hannah.

Link

 

[Zoa.Mania]

The reason this is important, there is a conversion you must do from phosphorus to phosphate. In your case 74ppb (phosphorus) would convert to 0.218 ppm (phosphate).

Forgot all about it. Probably since I use ULR phosphate checker.

So 0.2 phosphate still a bit high IMO but I know some systems doing just fine with that.
If you don’t experience any problems like algae and all corals looks ok (especially sps) I wouldn’t bother lowering the rate, just keep it stable and make sure it doesn’t spike again.