I have play sand in one of my 55 gallons and in my 180 gallon with my stingrays. RINSE, RINSE, RINSE. The more you rinse the less time you will have to let it settle. I just dumped the bag of sand in a big bucket and ran the garden hose in it for about 4 hours til the water ran clear after you stir it up. Put it in my tanks and was crystal clear in about 10-15 minutes.