The Importance of Pure Water

As growers expand, irrigation systems need closer consideration to produce a high-quality crop

t’s the challenge on every expanding grower’s mind: how to reliably scale premium, boutique cannabis to commercial volume. The answers are complicated and, to a large extent, highlight the struggle most small- to medium-sized growers face as they branch out to the big time. And many expanding businesses overlook a basic, fundamental element that can leverage the success or failure of a growing company: water.

Water as a monitored input is almost unheard of in typical commercial agriculture operations. After all, the goal of industrial farms is typically volume, not quality. As big players from traditional agriculture step in to mentor the emerging cannabis industry, serious caution should be taken, as irrigation methods that have worked for decades with other crops simply do not apply to cannabis. As a matter of fact, many of these methods can actually inhibit proper growth, undermining an otherwise perfectly engineered operation, because of water chemistry’s effect on nutrient bioavailability.

As growers scale up their operations, irrigation methods are increasingly important.

Tap and well water, though plentiful and cheap, are typically high in total dissolved solids (TDS), particularly magnesium and calcium carbonates. On the surface, this might actually sound like a benefit — after all, plants need calcium for healthy connective tissue and magnesium for robust photosynthesis, right? Absolutely true. However, it’s the carbonate form of these compounds and their large molecular weight that’s the problem. The molecule size is simply too large to be absorbed by the plant at an optimal rate. Regardless of how dialed-in nutrient formulas might be, there’s no overcoming sluggish nutrient uptake due to clogged root pores, commonly referred to as “nutrient lockout.” The solution requires two steps: strip everything out and then add back what is necessary for optimal plant nutrition.

The most cost-effective way to generate pure, low-TDS water at a large volume is commercial reverse osmosis. The largest, top-shelf cannabis growers in the world use this method, creating a massive, pure-water nutrient formula base, at a volume of up to 1 million gallons a day. Since every location’s water will have a unique chemical profile, these systems must be custom built. But the return on investment for these systems — typically a fraction of overall buildout costs — comes quickly once the results are realized.

Another growth issue to consider is how a modular, upgradeable reverse osmosis system can scale as the operation scales. These systems typically cover a range of about 10,000 to 100,000 square feet, without having to completely replace the existing unit. Modular filter membranes are added as the need for pure water increases. For facilities exceeding 100,000 square feet, larger and less flexible commercial water filters are installed with redundant systems, duplicate units that are either kept online to deliver more water or are used as a failsafe in case the primary system goes down. For the top-shelf industrial grower, losing a pure-water base for even a short period of time can be devastating.

Furthermore, as water usage and discharge regulations begin to influence an already complex path to planning a legal cannabis facility, water filtration also needs to be planned accordingly. In areas with limited access to water, reclaim systems recycle whatever is left over, strip out both nutrients and impurities, and then push the water back into the system. Reclaim systems are critical irrigation infrastructure if local laws limit the amount of discharge a facility can produce. Fully implemented reclaim systems not only reuse onsite water, but also recycle condensate, creating the potential for zero waste. Evaporation units separate water from sludge, with only concentrated dry waste remaining after a full cycle.

In the immediate future, the dividing line between success and failure will be the ability to produce top-quality cannabis on an industrial scale. Since growing premium cannabis at volume is far more complicated than in a small setting, many large companies will likely go under, giving smaller businesses a chance to scale up. Being smart about taking that giant leap forward means paying attention to the details that produce a shelf-worthy product.


Richard Gellert is the founder and president of HydroLogic Purification Systems. He began selling hydroponic water filters in 2005. Since that time, HydroLogic has gained an 80% market share of both professional and hobbyist growers alike. With 20-plus years of professional industry experience, he is recognized as a leading expert in water quality engineering, facility discharge, reclamation systems and regulation compliance. This article was originally published in the Summer 2018 issue of SunGrower & Greenhouse.


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