also depends how rich your food is. you can feed your fish but sometimes if the food is too rich, that might also cause algea to build up quicker. I just heard this from a guy so if I'm wrong, don't blame me.
At least in my case, the food is not likely the cause of the problem - most of what I feed them are spirulina based and I only feed enough for them to eat in 2 - 3 mins. I don't see any that get sucked up into the filter...