[header] How to clean a saltwater tank [title] Remove uneaten food. [step] While you should only be feeding the fish in your tank enough food for them to consume within an hour, there may occasionally be food leftover. Take a net and skim the uneaten food out of the tank. 
Do this an hour after you've fed your fish. [substeps] If you leave uneaten food in your saltwater tank, it can decay and make the water cloudy.