How Much Nitrate Is Too Much For Fish?
How Much Nitrate Is Too Much For Fish? Nitrite levels above 0.75 ppm in water can cause stress in fish and greater than 5 ppm can be toxic. Nitrate levels from 0 – 40 ppm are generally safe for fish. Anything greater than 80 can be toxic. Is 20 ppm nitrate too high freshwater? Levels