I put a bag in my ten gallon tank about a month ago, mixed with the bag of black gravel I already had in there. It was a b*tch to rinse but I managed, in a big pot, lots of water changes, stirring and dumping and refilling. I did about a third of the bag at a time and it took me about 15 minutes to finish it all. Had a little cloudiness in the tank (I didn't pour over a saucer), which cleared up by the next morning. Personally, I'd be willing to pay a few bucks extra if they'd rinse the damn stuff thoroughly at the factory and dry it out again before bagging it up. Oh well.