What in my swimming pool would cause sores on the bottoms of the feet or rashes on the buttocks?

== == You can get sores on the bottoms of your feet just from bobbing up and down on the floor of the pool. The surface seems smooth enough, but over a period of time, it will make the pads of your toes and feet raw. Sitting on the side of the pool can do the same thing...friends have stone along the side of our pool, and until it wore down some, the kids "cheeks" and finger tips (from grabbing the side of the pool) were raw. We came to the conclusion that it was the stone...the boys only had raw fingers and toes...guess the long swim shorts help with the "cheek" situation.

Check your PH and Alkalinity - if the pH and total alkalinity have been out of balance on the high side of the scale or test kit then you have calcium deposits. These can be as sharp as glass shards. Sounds like your pool has not been maintained properly and it also sounds like you are in for a pool renovation or at least an acid wash by a qualified pool tech.