I want to have a DSB for nitrate removal on my BB tank. But I don't want the sand in the main tank, the device/design can't be very heavy and it can't take up alot of room. I know its alot to ask for, but you are creative people. I tought of making water trickle slowly down through a 7"x24" cylinder full of fine sand. I'm not sure if it would work. thanks for any ideas.