I have 2 x platies, 1x peppered cory and a guppy. They all seem fine and are eating well again. 1 platie wasnt feeding. At the shop I was told 25% water change a week, but have discovered 30% is more like it and over 6 weeks thats a whole third of the tank. went away with work for a week and they were over fed, and not cleaned properly. Thats when all the trouble started. Any how, how to soften the water, Ive tried boiling it but to little avail, will get a charcole filter to see how that works on a litre and then test it. Not sure but thanks and back to shcool for me....ha ha ha ah