Water containing too much calcium and magnesium (called "total Hardness") may create serious problems. Contact your municipal water supplier who can provide you with an analysis of your water supply. If you are using well water, there are many laboratories that can provide you with an analysis if you send them a sample. If the dissolved salts in your water supply measure 200 ppm or more, we strongly recommend that you obtain a water analysis to determine calcium content. Excessive calcium is the main factor in determining if your water is hard. If an analysis of your water supply reveals that the Calcium content of your water supply is greater than 70 ppm (mg/liter) you should use Hardwater FloraMicro. Hardwater FloraMicro provides rapidly growing plants with a combination of chelated micronutrients uniquely formulated for hardwater conditions. Other options are to collect rainwater, install a reverse osmosis filtration system, or use purified water. Do not use mineral or "spring" water, which can unbalance the nutrient solution, or even be toxic to plants.

My water is chlorinated, is this a problem?

Chlorine is highly volatile, it evaporates as soon as it hits the air. By the time the nutrient solution reaches the roots, the chlorine is gone.

I understand the roots also need oxygen. How do they get it?

In a properly functioning hydroponic unit, the roots receive oxygen from the air which surrounds them, as well as from the oxygen which is dissolved in the nutrient solution. The proper medium can play an important role in this process.

Information in this section provided by General Hydroponics