tropic marin p04 test kit accurate?

[autoponicz]

just picked one up on a sale at the LFS and just wondering if anyone uses this kit or know how close to accurate it might be.....tries it and it says i got no p04....0,01 mg?

also what is the "c" bottle for?

 

[autoponicz]

nobody uses this test kit?

 

[grundig5]

I used one a few times. It said I had no phosphates, which was proven false with a calorimeter (had .13). IMO, a calorimeter is the only reliable way, although I have heard good things about the Elos PO4 kit.