Recommendation - More Scavenger Fish?
I recently bought a 20g tank that has a water filter, lighting, water heater, gravel rocks at the bottom, 3 ornaments, and an artificial plant. I keep the water at about 76 degrees Fahrenheit. My stock is currently 3 White Cloud Minnows, 5 Rasbora Hetermorphas, and 2 Albino Cory Catfish. After feeding the fish, I notice that the White Cloud Minnows and Rasboras tear up a significant amount of food in the top and middle layers of the tank. I also notice that the Albino Cory Catfish try to eat it as it floats downs. Unfortunately, there is still a lot of food left over at the bottom of the tank. I bought the 2 Cory Catfish to be scavenger fish and clean this up but I am not sure if I have enough of them. The food I use is TetraMin flakes and TetraMin granules. I have significantly reduced the amount that I feed them at one time (only what they can eat in a few minutes) but I still see food at the bottom.
Looking for any recommendations, should I get another species of scavengers, more Cory Catfish, etc...
Any help you can offer will be greatly appreciated.