This sounds like a massive amount of food for your tank. I usually give a few sinking shrimp pellets to cories if I think they aren't scavaging enough, and one sinking wafer every now and then as a treat for plecos... I used to put a few a night in for my plecos and my water was cloudy too. If you don't think your pleco is eating, I know of a simple test... is there ever a GIGANTIC string of excrement hanging off the little dude's underside? My plecos, with age, usually start eating my cichlid's floating pellets off the sides of the tank (they swim up, suck onto one, and drag it down, you can see the pellet as it is devoured pressed against the glass). I stopped owning cories when I stopped owning fish that didn't eat them, but I thought they stayed pretty plump off a little extra sinking food here and there, and as every pleco I've owned has gotten bigger, they get real smart about eating (try a vacation feeder block with a group of small guys, they are voracious).
