I've been trying to get some good test results on a pool that I know has iron in it. I know this because I just did stain removal on some really bad iron stains that covered the entire pool. I've tested several times at different stages of stain removal, most recently when 99% of the staining was gone. In all of the tests, I came up with 0.1ppm.
I've read that sequestrants may interfere with test results for iron. I believe I also read somewhere that if you wait longer, the test will eventually account for the sequestered iron. I let a sample sit for about 8 hours today, and it still only said 0.1ppm. Is there any way to get an accurate reading on the iron in this pool?
I've been using a LaMotte test kit. It has a tablet, and then I add 5 drops to get a color change if iron is present.