Here is some information that may help. The MSDN shows the reagent is somewhat harmless.

http://www.blueworldaquatic.com/pictures/HI713-25.pdf

Ken - BWA

Three pages and it still doesnt say what the regent is, other than "white powder"?

It also states "Do not discharge into the drains/surface waters/groundwater’s."

How many of us are dumping it down the drain? I know I do.

Here is a thread on Reef Central which looks at the accuracy of the phosphate checker:

http://www.reefcentral.com/forums/sh...php?p=17068002

I would really like to know what the low limit of detection of phosphates is for the phosphate checker. Both my reef tanks read 0.00 ppm phosphate and I don't believe the phosphate level is really zero. I will set up an experiment with serial dilutions to see how low a level of phosphate is detectable by the phosphate checker.