If the tanks been set up for a year, it should be cycled, but its not guaranteed. Certain things can wipe out entire bacteria colonies in a well-established tank. I'm not a big fan of the undergravel filters, but some people like them. One big problem is if you don't vacuum the substrate, pockets of anaerobic bacteria can build up and cause outbreaks such as the fungus or eye cloudiness you're observing. I have used the ammonia chips, but I'm not sure how well they work. For initial treatment raise the temp to between 80-82 and add some salt (someone else can chime in for the dosage). You may end up having to treat with antibiotics or fungal treatments, but see how they respond to heat and salt. Add aeration if the fish seem to be breathing heavy.