I have a fully cycled (0 ammonia, 0 nitrite, minimal nitrate) 20 gal tank with 8 platies, 8 neon tetras, 3 zebra danios, and a bushynose pleco. The only issue I have is with the city water supply being very soft and thus acidic. Measuring the KH and GH I get 17.9ppm for each (both turn to...