 For hydroponic uses, total dissolved solids is considered one of the best indices of nutrient availability for the aquatic plants being grown.Because the threshold of acceptable aesthetic criteria for human drinking water is 500 mg/l, there is no general concern for odor, taste, and color at a level much lower than is required for harm.A number of studies have been conducted and indicate various species' reactions range from intolerance to outright toxicity due to elevated TDS.