I have 2 red sea test kits and they give different readings. I am willing to pay the money for the best kit, but there are so many out there, I am not sure which one is the most reliable. I can get a "Hagen Master dealers" kit for around $90.
Salifert are the most reliable that I have tried, but they too give me 2 diffrent readings back to back sometimes. Also as cheap as tetra tests are, I have had pretty good luck with them too.
Kyle
I have had no problems with Salifert tests...readily available...accurate...and not too expensive. There are a few other quality products...hagen & Lamotte...but salifert has been fine for me so far.