Test Kits

I want to think Kevin & Paul for sharing their info with the rest of us.  I'm 
anxious to try out some of their ideas. However, it is obvious that 
experiments are useless without accurate measurements of the data involved. 
And that brings me to my question; Who makes quality, affordable test kits? I 
have a Sea-Chem phosphate test kit, and I'm not impressed. What did you guys 
use? And anyone else that has any info on test kits, feel free to share it!