I see a lot of foreclosures that have pools that are swamps. I would guess that 50% of them have these strange white cubes in them. There is usually around 5 in the pool. They are about 1 inch by 1 inch. I have never once seen them in a clean pool. I had always kind of assumed it was something that the people who were living at the house put in the pool. However recently i cleaned a swamp, then the realtor was supposed to maintain the pool until the house sold. He didn't do anything and within a month the pool was a swamp, when i went out there today these cubes were in the pool. So in this case i know nobody put these cubes in the pool. Another observation with the cubes is they always seem to be spaced an equal distance from eachother, i dont know maybe im just imagining that. I have a picture on my phone but i am not really sure how i get that on to the website. Let me know if you have any guesses.