which phosphate test kit is reliable?

[o2bubble]

Hi all, any recommendations of which one I should get to get a good result on phosphate level in my tank? Already got Ammonia, Nitrite, Nitrate, PH, KH/GH test kits. Thanks!

[uklau]

Only test kits that are calibrated properly will produce good result .

[o2bubble]

Just bought the canada company brand type - Aquarium Pharmaceuticals. Hope its accurate.