No... pool filter is pretty much clean, since it's used in, guess what, Pool filters!. It does make the water quite cloudy for about 12 hours... but all those tiny grains will settle as bacteria colonize on them. Same goes for any other type of sand... the tiny grains of sand that floats around after you dump the sand in will all become part of the sand bed. It's when sand has a bunch of dead organic matter in it that you want to rinse it out... Dead organic matter is not good, since that decomposes and impacts water quality via becoming nutrients in the water.