I'm extremely unhappy with my Lamotte phosphate kit. I'm not sure if it is bad (although I just bought it), I'm doing it wrong, or what -- but it is extremely confusing with the ampule of distilled water and mirrors. Even adding Fleet enema to the water sample, I get a zero reading if viewed as directed through the ampule of distilled water provided. There is color in the sample if I didn't use that stupid ampule. All in all, I think it is a very difficult to use test.