I'm Stumped

[Wizzard~Of~Ozz]

for the longest time I always had water that was less then clear, sort of like micro particals floating in it. well today I added 2 caps of phosphorus (20ml or about .2ppm) and the water cleared right up. I mean it's almost crystal clear.. I was worried adding it because of green water.. but no such thing..

My AP test kit said my PO4 was @ 2ppm. but I was getting green spot algae so is there a problem with the AP test kit?

[BlazerFRS]

I could never read my AP test kit... the color differences were just too subtle. I've also heard it's less then 100% accurate.
I've since purchased the seachem kit, and am pleased with it.

[travis simonson]

I agree with BlazerFRS, the AP test kits can be hard to read and may not even be accurate to begin with. The Seachem kit is a great one for the price and is quite easy to read. Plus I trust Seachem products.

[Simpte]

There are no good "hobby grade" PO4 test kits. WOuldn't even worry about them. PO4 will not cause greenwater. It is induced 99% of the time by NH4. Once induced, it will feed on NH4/No3 readily.