There are many different parameters with different “healthy levels” for each species. For example, healthy levels for Angel Fish look like: -pH: 6.5-7.5 -KH: 3-8 dKH -GH: 4-10 dGH -Ammonia: 0 ppm -Nitrate: Below 20 ppm -Nitrite: 0 ppm -Alkalinity: 80-120 ppm (or 4-7 dKH) -Temperature: 76-82°F (24-28°C)