A couple of months ago i had an outbreak of skin slime disease and treated with Protozin.2 male guppies and 2 females died but the rest of the fish seemed ok. I have been doing the usual tank maintinance and other than my nitrates staying a little high 40-80 everthing seemed ok. 2 weeks later i lost another female guppy but couldnt see why,so i dosed again. I thought even if its not down to the same problem it couldnt hurt. 6 days later, after finishing the course, everthing seemed fine and i replaced the dead fish and all seemed ok till 4 days ago when i noticed a white lip on my new male guppy and a white spot on one of my neon tetras back.I spoke to my fish shop supplier and bought a more indepth water test kit and some more Protozin. The reading were as follows Nitrate 50-60, Ammonia 0.1, PH broad range 7.0-8.0, Nitrite 0.1. Today i lost the guppy. Please can you help with any suggestions and anything you can recommend i try?