It really depends what sand you use..... if the sand is very fine it will compact quickly and cloud up water every time a fish goes by! Silica Sand is very good for aquariums...! usually people buy playsand cus its cheap and it really can mess up a aquarium.. ! I agree i can get dirty very quickly... but all you need to do is skim a hoover over the top once or twice and its clean again!! Also i think Bichirs benifit from sand... they eat it and it helps them digest food,,