18
GROW WITH JORGE CERVANTES
By Jorge Cervantes – jorge@marijuanagrowing.com
WATER SOURCES Sources of Water: Air conditioner water: Water condensed from an air conditioner or dehumidifier is very clean—virtually no dissolved solids. But the water does trap cannabis fragrance. Most A/C units generate 2 to 7.6–11.4 liters of water a day. Empty containers on a daily basis! Rainwater: You can harvest 2000 liters of rainwater from 3 cm of rain that falls on a 93 m2 roof. Although slightly acidic in urban areas, rainwater is free of chlorine and pollutants or salts that normally occur in groundwater.
prevent evapora- tion and keep out trash. To make sure it is not too acidic (acid rain) and harmful to plants, take pH and parts per million (ppm) readings from collected rainwater before using. Rivers and streams: Usually, these water resources are publicly controlled. Alpine watersheds supply “mineralized” water— water with elements and nutri- ents that plants need to produce food and grow. Tap water: Household water often contains chlorine and other dissolved minerals. Check two or three times a year with your local water bureau to find out
out the sodium, then siphon water from the top of the barrel, refilling after each watering to allow the chlorine to evaporate. Chlorine, like sodium, is beneficial in small amounts. It is essential to the use of oxygen during photosynthesis and is necessary for root and leaf cell division. But too much chlorine causes leaf tips and mar- gins to burn and leaves to turn a bronze color. Chlorine (which evaporates) and chloramine (which must be filtered to remove) are added to household water systems to kill bacteria, parasites, and other organisms. But both oxidize iron, manganese, and hydrogen sulfide, making them easier to filter out. Empty the
and over time. Do not assume that the mineral content will be the same as that of your neighbors’ well water. Most often well water is hard, with high levels of calcium and magnesium.
Purified Water Bottled water enjoys minimal regula- tion in most countries. The US federal government for example, requires that bottled water be at least the same quality as tap water, but some studies show it is of lower quality. Frequently sold as “mineral water” for $1 to $4 USD per 4 liters, bottled water may contain more dissolved solids than tap water. If you are using bottled water, read labels care- fully to ensure that it contains less than 150 ppm (15 mg/L) dissolved solids (aka minerals). Carbon filters are effective at removing chlorine, chloramines, sediment, and volatile organic compounds (paints, petroleum solvents, and hazardous wastes) from water. But they do not remove dissolved mineral salts from water. Use carbon filters as a pre-filter to reverse osmosis (RO) filters. Deionized (aka demineralized) water has had its mineral ions removed. A water deionizer moves water through special ion exchange resins, complex sodium salts. These resins bind to the mineral dissolved solids (salts), filtering them out of the “pure” water. Deionized water is similar in purity to distilled water. Deionization does not specifically remove viruses or bacteria. Distilled water has many of its impuri- ties eliminated via distillation, a process that boils water. The resulting vaporis captured and condensed into clean water. Purchasing distilled water is very expensive: $0.75 to $1 USD per 4 liters. But home distillation systems can cut prices to $0.25 USD per 4 liters. Distilled water is available at most grocery stores and home improvement centers. Gardeners often use distilled water for cuttings.
Piping water into the garden facilitates irrigation.
Clean rainwater is an excellent choice for irrigation. Collect runoff by plac- ing a barrel under a downspout. Mix the rainwater with tap water to dilute dissolved solids. Roofs and terraces can accumulate trash, which will pollute the otherwise clean rainwater. Covering your catch-barrel will
what is in your water. Also check the pH regularly. See discussion above about water sources. Clean your tap water by filling barrels and setting them 61–91.4 cm above the ground. Add ammonium sulfate to settle
barrel periodically, and scrub out residues and sediments. Well water: Ground water is pumped from a well. Have your well water analyzed at least once a year because mineral content often changes with the seasons
Electrodialysis-filtered water is most economical to use in large- and medium-scale installations when desalinating brackish water and seawater. Smaller systems are also available. This process is most efficient when removing ionic components with a low molecular weight. Water microfiltration systems remove suspended solids down to 0.1 micrometers in size. Use microfiltration as a
