I think its good to replace all the valves. Else if the current valve gets damaged you will have to repair it again. Recently, I also cleaned my pool. For few days we were not at home. When we reached back we saw a raccoon lying dead in the pool. We immediately called one of the wildlife control services in Newmarket to get the pool cleared of the dead raccoon. There are also a lot of raccoons in the attics and in the yard. All those raccoons were also caught by them. Raccoons like to hide their feces in the water, so they often poo in the pool, often on the first step. So it was a need for me to get my pool area and surroundings cleared of those dirty creatures.