Hanna Checker Phosphate ULR versus Colombo and Salifert test kits

[Peter Brom]

HI,

Im using the Hanna Checker Phosphate ULR for a while now and im not sure if it gives the correct reading. Today i did a triple-check and got the following readings:

Hanna: 0.7 (first reading was 0.8)
Colombo: 0.0 (double check)
Salifert: 0.0 (double check)

Not sure what to trust here. Does anyone had the same discrepancy with the Phosphate ULR checker? and what to do here ?

Thank you replying.

Ps All my other Hanna checkers are fine and double checks, they give the correct readings.

 

[blaxsun]

I'd run another Salifert test or two.