Marijuana Business Magazine September 2019

One RO system can fill a 3,000-gallon tank; on a heavy day, Cesario’s team will process roughly 8,000 gallons for 25,000 square feet of canopy, which is irrigated with a hydroponic system. The RO water is at least 99% pure, Cesario said. His team then formulates nutrients to add to it. “It’s like a clean slate,” he added. “You really have to balance your feed based on the water source.” But that water doesn’t want to stay pure. “It’s subject to wild changes in pH,” Cesario said. To stabilize the pH, he adds a “buffer” that typically includes potassium bicarbonate. A common pH range for water is 5.5-6.5, but that can vary depending on the strain, grow media or the stage of the plant’s life cycle, according to Cesario. While the expense for the RO machine can vary based on a number of factors, including size and amount of filtration, Cesario said the price consumers pay for cannabis justifies the equipment cost. “It’s such an intensely grown crop and such a high-value crop,” he said. “It’ll help you achieve your maximum potential.” Working with an RO system and building a nutrient program around that pure water also helps Cesario’s team develop standard operating procedures in other states where Green Thumb Industries operates. That “clean slate” water can be replicated, provided the out-of-state grow operation also uses RO. One criticism of RO is that it can be resource-intensive. Often, the dissolved solids that are removed from the water reduce the overall volume considerably. To help conserve moisture, Cesario reclaims condensation that forms around the HVAC system. As far as maintenance, his team tests the machine and water frequently—as often as every day— to ensure everything is flowing as it should. Rain Catchment In Humboldt County, Cali- fornia, David Digiallorenzo, owner of Casa umboldt, sources his water from the sky. It rains enough that if Digiallorenzo can collect rainwater properly, he’ll have water all year long. Digiallorenzo’s tanks can hold 80,000 gallons of water—enough to irrigate two 10,000-square-foot sections. He’s never had to use supplemental water to make it through the year. Best Practices In Cultivation | Bart Schaneman