Brine shrimp is not nutritious to the fish at all, I have heard people comparing it to us living off of potato chips. It is okay for the odd treat now and then but i would suggest you get mysis shrimp. I feed my tanks a variety of mysis, blood worms, flakes, and a small amount of brine sometimes. When you feed do you use the whole cube? If so that is way too much and would definitely encourage algae growth. Feeding every other day is actually recommended for saltwater fish (unless you have something like a seahorse which needs multiple feedings a day), feeding every day is unnecessary.
Also when feeding with the cubes you should thaw the cube and rinse the shrimp before adding it to the tank. The gunk the shrimp are frozen in will pollute the tank more. I use a small cup with some water in it to thaw the shrimp then either tweezer the amount i need out or use a net to strain it out.