I was feeding 2 times a day and was having same problem lots of poop. I have a silica sand substrate so it would look bad even a day after wc. I cut back to once a day and I skip 1 day a week. It has made a big difference in the amount of waste.
I put mine on a diet a couple of days ago and I also have noticed a LOT less poop in the tank. I think I'll keep the once a day feeding.