I agree with fort. Feed less food and you'll have fewer issues with excess food and algae. As for poop, what goes in must come out. It doesn't dissapear when the bottom feeder eats it.
Additionally, I would wait 6 weeks after the last fish death before adding new fish. This would be a good opportunity to get a QT set up for your new arrivals.
I recomend you go to the pet store's aquarium plant display, and look for the most snail-infested plant to take home. Bring that home and leave in QT for 4-6 weeks. Those common pond snails are pretty good janitors, and will breed to the number that matches your tank's bioload.
All bottom feeders will turn excess food and algae into poop. You need another way to remove the end products from the system. You have to do regular bottom vaccuming.