Avoid pellets... it's better to feed meaty frozen foods like enriched brine and mysis shrimp. It doesn't take much to feed em'. And, you will end up cutting off a piece of a cube every day. pellet foods add too many phosphates to the water - which in turn will make your cyanobacteria worse.
Is it the Aquaclear 50? It's adequate. Adding another might look like too much flow but it would make for a healthier tank. The only downside might be the additional heat if you have temperature issues in the summer months.