API Phosphate Test Kit?

that exactly what want.........thanks a lot for all of yours advice. i ll following what u said.;D

 

I had all those test kits mentioned, and more, including a phosphate photometer, and now in hindsight, I'd say the only essential ones are, if its a new tank that's cycling, you need ammonia and nitrate. once cycled, you would initially need calcium and alkalinity for determining if you need dosing and how much. you will need the high range ph as well if you do not have a controller with ph probe, but ph tester is the cheapest of all. as for phosphate and nitrate after the cycle, you can just look at your tank, if it has algae, then it has either phosphate, nitrate or both. as for magnesium, as long as you use a good salt and do your water change, you don't need to test magnesium.