Dmaaaax I think my chemistry experiment causing some negative effect on my fancy guppys. They developed some type of white (looks like small piece of coral) fungus on the bottom of their mouth. Two of them stop eating (both are female), but they are still active ...
The only things was added to the water is baking soda (1/8 of tsp on 4Gal)
and Excel 2ml on 4Gal recommended in the bottle for initial setup

Any idea?

Thanks