Improper pH ranges can also result in precipitates (calcium sulfate), a white cloudy or powdery looking substance that can float or even settle at the bottom of your reservoir. When the pH of the nutrient solution rises above 7.0, a chemical reaction can occur causing the calcium to bond with sulfate and other trace elements like iron, copper, zinc and manganese causing them to become unavailable to the roots. It can even cause problems with emitters and/or misters clogging, and buildup in the growing medium, and in extreme cases can cause plumbing blockages or restrictions (like clogged arteries). The exact pH that precipitation of the nutrients begins, depends on the exact concentrations of calcium and sulfate in the nutrient solution. But it typically can begin at 6.5, unless the particular nutrient solution is low in concentrations of calcium and/or sulfate. Generally speaking, higher nutrient concentrations are more likely to result in precipitates, than lower concentrations.
