Water is the life’s blood of any grow operation, but it is not sexy and often overlooked. Why is water important? Pure “clear” water gives you the best opportunity to develop precise nutrition recipes to boost your yields and increase your potency, and that means increased revenue and more money in your pocket. Accurate grow recipe development requires control over your water chemistry to enhance the cannabinoid profiles of your healthy, potent flowers.
Pure or “clean” water is the beginning of a successful grow operation, whether in soil, media, hydroponics, or even advanced aeroponics. The more precise your water, the more accurate your grow recipe. Water can also be a money-saving resource because you can recycle it and reuse it over and over again. So, how do you get to pure, reusable water?
Water is effectively a balloon. Ideally, you start with water that is like an empty balloon, i.e., purified, so that it is clear and ready to accept and carry the exact nutrient salts that you add in precise quantities (your nutrient grow recipe). The problem is that water (sourced from surface water, or well water, or even municipalities) comes with various salts, metals, sediments, particulate matter, and in some cases, various pollutants such as bacteria, parasites, viruses, or chemicals. For direct control, the cultivator has to “clean” their water to precisely manage their grow recipes. If you start irrigating with a full balloon, it doesn’t matter how much nutrient you add, it will never get to your plants in the precise quantities you want.
Incoming water is a good starting point. Test your incoming water so you know your initial challenges. One cannot assume that the results will always be encouraging; it is essential that you monitor your water and continue to test it over time to guarantee your foundation.
Common Starting Point: Municipal Water
Typically, at a municipal water plant, the first cleaning stage is to clear negative ion materials and to coagulate these solids from the water. This is done by adding positive ions like salts or metals to the flow. Solids that are produced are coaxed together into what are called flocs or flocculates. Flocs are filtered out in sediment ponds or containers.
After the light water clears the sedimentation, it is typically put through reverse osmosis (RO) where high pressure water is forced through membranes with very small filtration openings. This clears out the remaining larger molecules. It is common practice for cultivators to repeat the RO with their incoming water. Pure water leaves the treatment plant but that water picks up materials as it travels through the pipes and pumps on the way to your shop.
A final step done in municipal facilities is to use chlorines, ultraviolet lights, or ozone to clear bacteria, parasites, or viruses from the flow. This low-level chlorine is left in the water to maintain a low level of contamination as it transports to the user destination through pipes and pumping systems.
Is it Worth the Trouble?
If your water supplier does all of this for you, why bother duplicating the process inhouse? Environmental conservation is a feel-good reason but water recycling can save your operations significant expenses, while at the same time, improving the accuracy of your nutrient grow recipes. There is one easy truth — better grow recipes grow bigger more potent plants faster, and that means more revenue for your crop.
When you depend on pure clear water for your operation and you want to recycle your used water, you need to duplicate many of these filtering methods inside of your own operation. These typical processing operations are incoming supply, recovery of nutrient reservoir water, and photosynthesis humidity capture and reuse.
Water that interacts with your plants and the environment in your rooms will always carry symptoms of your plants and anything they are exposed to in the environment. It’s best to always plan on re-filtering your water inhouse and treating it to clear anything encountered along the way. You will be rewarded for this investment with repeatable and predictable results over time.
Real World Example: RAIR, A Vertically-Integrated Aeroponic Cultivator
RAIR, in Michigan, operates 22,000 square feet of aeroponic cultivation using a complete water recycling process that reduces their monthly water bill to a few hundred dollars, a 95% savings (approximately 50,000 gallons per month). They also produce large yields of high terpene content plants produced in a continuous weekly harvest operation. Pure water gives them direct control over their precise grow recipes with consistent results under continuous improvement.
RAIR uses several methods of water recycling to reduce cost and increase accuracy and they are an excellent model to follow. Ashley Hubbard, director of cultivation at RAIR, uses carbon filters, chlorine bleach, Greensand filters, ozone, and ultraviolet filters, to accomplish the task. Let’s go through their methods for incoming water treatment, humidity recapture, and nutrient flush recovery methods to give you a brilliant example of how this is done in practice.
Incoming Reverse Osmosis Skid
RAIR’s municipal water typically starts at roughly 125 ppm and includes low-level chlorine and residuals. Their treatment process uses two carbon filters to screen out any remaining disinfectants or biologicals that were picked up in transport to their facility. That’s followed by reverse osmosis filters to screen out remaining elements, driving the remaining particulates below 5 ppm. Getting water through the RO process generates a good deal of “wastewater.” RO wastewater can be treated just like grow recipe nutrient wastewater and treated again as seen below.
Nutrient Dosing Water (Fertigation) Recovery
RAIR uses AEssenseGrows aeroponic equipment which automatically mixes nutrient salts with clear, purified water for a precise nutrient dosing grow recipe that is sprayed on the plant roots with irrigation schedules and timing. As the plants absorb nutrients from that spray feed, the nutrient mixture is returned to the reservoir, tested, re-dosed to get the nutrients to the proper level, and the plants are irrigated again on the next irrigation cycle.
Periodically, the liquid remaining in the nutrient reservoir is “flushed” or removed so a new, more precise nutrient batch can be remixed for the next stage in flower development. This flushed water is recycled into the second recovery skid along with the surplus municipal RO wastewater. This section of your recovery system is a heavy filtration system. Active nutrient salt fertigation grow recipes will range from 1200-1800 ppm levels depending on the stage of flower. Here, the filtering process begins with a more robust chlorine bleach injection to clear bio-objects like viruses or bacteria that may have entered the grow nutrient reservoirs. This stage also uses heavy metal filters (like Greensand) to filter out nutrient salt metals, and finally RO recovery again to filter out the remaining particulates generated in this stage. Used nutrient fertigation liquid exits the reservoirs at approximately 800 ppm and this filtering stage clears the content to approximately 6 ppm.
HVAC Humidity Recovery Skid
The third and final water treatment skid in our example recovers humidity in the heating, ventilation, and air conditioning (HVAC) system. Humidity reclaimed from HVAC water is essentially distilled water (ppm < 10 ppm) but in our grow room case, it will have some level of microbial life that has to be eliminated to reach reuse purity. Again, the same methods of cleaning are used but with more intensity in the microbial area. Starting with a chlorine bleach injection to kill microbials, the dual carbon filters follow for large and small filtration of metals and dead microbials. This stage increases the ultraviolet light purification with the addition of ozone purification for a period of time in the storage tanks, and follows with deionizing filters, and a calcite filter if the pH of the water needs adjustment.
To watch the live discussion of this complete example, you can see a live walk through tour in a 10-minute episode here RAIR’s treatment room.
Since water is such an essential contributor to a successful cultivation business, it is imperative to benchmark your water supply before you get started, and build a monitoring and cleansing process into your daily operation. This will save you as much as $60,000/month in our example. Understanding the quality of your water will also enable you to make precise updates to your plant nutrition grow recipes and irrigation schedules to grow amazing plants to delight your consumers. Make the investment; you will not be sorry.