If you have lots of wasted food, you're definitely overfeeding. Stop doing that, and learn what those two clowns can consume in less than three minutes. Once you know how much they will eat in that amount of time, feed them only that amount. No more. Anything more is only polluting your tank. I know they seem voracious at mealtime, but a hungry fish is a healthy fish. If they overeat, they create massive amounts of poo, and if they don't eat all the food, it decays in the tank unless you have a large enough CUC to handle it. It's a good idea to get the critters Flower mentioned, and if you start seeing nuisance algae, include Astrea snails as well. They eat film algae as well as hair algae. A good variety will cover most scenarios that can arise in saltwater tanks. A lot of online vendors offer CUC packages that can save you some dough over individual species purchases.