Salifert Po4 vs Hanna Phosphate ULR

[Auburn866]

Questioning the accuracy of my phosphate test kits. I've been fighting Dinos, and was dosing silica which caused my Hanna to read much higher. I've stopped dosing silica over a month ago, and did multiple water changes but it appears my Hanna may be still reading much higher than actual. I bought a Salifert Po4 kit for comparison, the salifert test kit reads around .1PPM while the Hanna reads .3 PPM, not sure which one to trust. Also on the salifert, it says in the instructions to swirl the water for 30 seconds after adding the 2nd part but the reagent never seems to fully disolve, is this normal?

 

[exnisstech]

I've not used salifert but here's a Bump

 

[Randy Holmes-Farley]

I don’t think it is correct that silicate made that reading difference, but both are adequate for driving organisms that compete with dinos for space.