I've always had at least a 10gallon tank for all my fish. This is the first time I've had anything in a 5.5gal. It's water-change-weekend, and usually before I do water changes I vacuum the gravel. However, my gravel vacuum requires there be a certain depth of water for it to be able to work correctly, my 5.5gal is too short for it to work. Any tips on cleaning the gravel bed to get the poop/waste up before I do a water change? Thanks.