Are those the 1.7 lb bags??? If so, that's about 15 lbs of food. I dont have any BIG fish inside. In the 600, there are about 50-60 fish ranging from 2" to 9" (the tiny guys are just a few Shubunkins) with a joke of a filter (this is where the new baby skippy went - but there are plants to help) and the 750 has 103 babies (delivered the first week of December) ranging 3"-6" (were 1-3" standard fin, and 2-4" butterflies) with a couple close to 7", which is running on a combo of spare parts ... nothing near as nice as your filtration system ... I just looked .. since October (when the plant pond was built and I bought seperate bags for the basement verses outside fish since I am too lazy to go up and down stairs just for food), we've been through one 5 lb bag Tetra Pond Vibrance, one 5 lb Tetra Pond Growth, and are about 3/4ths of the way through another 5 lb bag of Tetra Pond Growth ... On average, each pond is getting 35 gallons of new water a week (2, 35 gallon barrels of water always cycling) ... I have NO DOUBTS, with your system, we could put ALL of these babies in one pond. I havent checked the nitrates in a couple of months ... ammonia and nitrites are staying right at zero. Personally, I think as long as there is a good amount of area for the good bacterias to grow, it doesnt really make a damn bit of difference which type of filters we use. Some just take up more space than others.