We generally trust the water we get from our tap but what might we find in it if we did some research? Various chemicals or discarded substances are turning up in our lakes and rivers and may be affecting our health. How much do these substances affect our plants?
Fortunately for our plants, the types of impurities mentioned above are typically too low to affect plant health, but many plant species are known to absorb contaminants such as lead, cadmium, chromium, arsenic. We need to become and remain aware of what is in our water and keep it as clean as we can.
Along with the normal chemicals or minerals found in tap water, accidents can occur somewhere in the treatment and distribution system, which can add more serious contaminants. These incidents are not common but every gardener should stay abreast of any news that might be available from the local water authority.
Some of the issues a hydroponic grower needs to consider most include:
1. Hard water
Hard water represents the combination of calcium and magnesium in the water and is generally determined by your municipality’s source water. Keeping your pH levels low can minimize the damage hardness can cause to pipes and drip emitters. Most plants prefer a pH of around 6, which will also minimize any damage from hard water.
Iron is a common issue with recirculating systems, as it is found in most nutrient solutions and is required by plants. As iron builds up in the water, it can clog drips and cause brown staining. Iron can generally be removed by aeration followed by two days of settling.
3. Carbon Dioxide
Carbon dioxide is used by the plants for photosynthesis, but it is also present in water in the form of a dissolved gas and when mixed with Calcium and magnesium can form carbonates and bicarbonates and ultimately plug up the works.
Alkalinity is the term used to identify the level of bicarbonate in the water. Alkaline water raises the pH, while acid reduces pH. If the tap water you use is highly alkaline, it will raise the pH of your nutrient solution. Checking your nutrient solution frequently for alkalinity is important when high-alkaline tap water is used. It can be confusing when trying to control pH by adding acid if you don’t consider this whole action/reaction between the alkaline water, acid and carbon dioxide. High-alkaline water will resist change from the addition of a pH adjuster, and unless you aerate the water, the pH level will not be stable because the CO2 is slowly escaping.
Chlorine residuals in the water supplied to plants can reduce levels of beneficial bacteria when present in high amounts and can damage root growth and vigor. The use of available filters for these chemicals can help a lot. Good filtration will remove many contaminants from your watering system.