Get thee to the grocery store and buy a zucchini stat. Cut it n half lengthwise and de-seed it, attach a 4" long chunk of it to a piece of rigid airline tubing or rubberband it to a fork, whatever, and get it in there. Some will tell you to blanch the zucchini first to help make it softer. I don't do that. In the meantime, either get yourself some Kordon "Rid Fungus" or other fungus cure. I recommend the Kordon product because it can be used in your main tank without harming animals. It will also take care of ich if you have it. Algae wafers aren't enough for plecos, especially if you have no driftwood (you need driftwood for plecos) or a tank without enough veggies and/or algae to eat. Plecos are pigs. They will eat constantly, and are poop machines.