January 20, 2017
By Rich Gellert
Some cultivators are lucky enough to enjoy a clean and reliable water source that’s always readily available. Unfortunately, that’s increasingly not the case across the country. Hormones, pharmaceuticals, and all kinds of toxic materials are making their way into the national water supply. In drought-stricken areas like Los Angeles and San Francisco, “toilet to tap” reclamation procedures are now in place, essentially straining solids, dosing with chlorine, then pushing the water back into the public drinking supply. Sound gross? Well, the situation with water in America is rapidly changing. If you wouldn’t drink the tap water at your house or cultivation facility, why would you give that same water to your plants? One of the worst mistakes a cultivator can make is to invest money into a garden, but gloss over the water supply quality, perhaps the most important resource to having a genuinely healthy end-product. Even if you believe your geographic area has “good” water, not investigating the quality and serving your plants less than optimal water could choke their potential, and undermine an otherwise perfectly engineered operation. The TDS (total dissolved solids) in any type of untreated water varies for several reasons, and the relatively small investment into a water filtration system is a big step towards a consistent and reliable ecosystem.
Many cultivators use purified water to completely control the content of their nutrient formulas for each plant strain grown, making sure they properly and consistently dial in the amounts of each mineral vital to healthy plant growth. Getting a water test to determine source water quality helps cultivators to decide whether or not using a water treatment system would benefit their operation. Municipalities provide free water reports, though water quality fluctuates greatly throughout an area, over the seasons, and can even vary from site to site. A key indicator of water quality for plants is total hardness as expressed in the TDS of calcium and magnesium or in grains per gallon (gpg). With too much hardness, nutrient formulas can be thrown out of balance and plant deficiencies and lockouts quickly become a major problem. Any water source with over 50 ppm of TDS of hardness should be purified. 50 ppm of hardness translates to 3 Grains per Gallon and is considered soft water, which few facilities have straight from the tap.
Cultivators using microorganisms such as beneficial bacteria, fungi, nematodes, mycorrhizae, and trichoderma must have chlorine and chloramine-free water in order for those helpful microbes to survive and flourish. All municipal water contains chlorine and/or chloramines as they are both powerful biocides, meaning they are designed to kill all living organisms. Letting city water sit out and bubble overnight may get rid of chlorine, but it’s not effective to remove chloramines or other contaminants. Water from well or spring sources is often high in minerals such as calcium, magnesium, sulfur, and iron. Giving water with too high of levels of these minerals to heavy-feeding plants will contribute to nutrient lockout and lead to deficiencies. The following table shows the most common contaminants in water, their sources, and what harmful effects they can have on plants. As one can see, many dissolved minerals in untreated source water have the potential to damage crops.
Using reverse osmosis to filter source water is the single most efficient, economical, and reliable way to ensure the removal of 98%+ of all contaminants mentioned above. As reverse osmosis technology continues to advance, as well as new regulations go online, several simplified water filtration solutions for commercial and hobby growers are now available. These systems ensure consistency and reliability of water input and are critical to the professional grower. Already have access to excellent source water? Consider yourself lucky. The rest of the country is having to deal with increasingly complex and sometimes dangerous water contamination issues as seen in areas like Flint, Michigan and Corpus Christi, Texas. Remember, if it’s not healthy for humans, it’s probably not healthy for plants.
photo by liveoncelivewild.com