While I haven't left one in the skimmer basket, considered it once to see if it would absorb the oils or suntan lotions then remembered its not absorbent at all, I have used one to clean my eyelets, tiles, pump housings, and baskets. I also use one to clean my acrylic saltwater reef tank. The inert material is reef safe and keeps my tank clean without scratching the surface. neat hack is to take an old piece of PVC, heat about 2-3" down a little, compress it into itself then tightly ziptie the magic eraser to the pvc (can use rubber bands but I don't like rubber in my reef tank. then use the pipe as a handle and clean without getting wet. simply cut the ziptie when done, if any eraser is left, rinse and set aside for later.