Soil-based fertilizers are meant to supplement the minerals and matter in your soil. In many ways, this simplification of variables works in your favor in hydroponics. Hydroponic supply stores have a variety of nutrient mixes for specific crops and growth cycles. Always store mixed solutions out of direct sunlight to prevent any algae growth. For related discussions involving nutrient solution, see conductivity , macronutrients , micronutrients , mineral deficiency , and pH .
Any gardener needs to be confident about their water quality.
This is especially true for hydroponic gardeners. The water you use in your hydroponic system needs to be pure. It is always a good idea to test your water source before adding nutrients so you aren't adding an element that is already present. In small systems, it would be wise to use distilled water. If you are starting a larger hydroponic operation, it would be a good idea to have a water analysis completed.