I am running low on POP. I'm not sure where you can buy that!

To amuse myself, and because I am a science teacher, I'm running two experiments. In the first, I have a clear glass of pool water and am simply letting it sit to see if anything settles out of it. In the second experiment, I have another glass of clear pool water, but have added a tsp of dichlor.

I don't know if I'll see anything happen and if it does will mean anything, but I've just got to do something besides add bleach, test, brush and vaccuum.