Filtering out the nonsense

Ask the Experts - Water

Hawthorne’s technical services manager Bill Perryman gives his insights on water filtration systems, having worked nearly five years with Hawthorne after a decade of working in the engineering and design industry.

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April 19, 2022

Photos courtesy of Hawthorne Gardening Company

Greenhouse Management: Why is choosing the right water filtration system so important?

Bill Perryman: There is no one “right” water filtration system for every situation. Water filtration is part of an overall 360° growing plan involving many categories, each impacting the next. The first stage of a water filtration system is understanding the desired outcome. The right water filtration allows for controlled plant growth science, conservation and maintenance. Water filtration that’s properly designed, sized and operating as specified can ultimately help lower operating expenses and aids in plant growth.

GM: How can using a quality filtration system contribute to producing a healthy plant?

BP: Many things contribute to a healthy plant, such as growing environment, growing media, lighting, nutrients and yes, even water. For many large-scale operations, we find it best to strip the water down of its assorted salts using reverse osmosis (RO) so that the grower may replace the undesirable salts with nutrient formulas, targeted to the plants’ specific growth stage. Controlling, monitoring and documenting water parameters not only helps a grower to understand how certain changes affect a plant’s growth, but it can allow for the process to be a launch point for a workflow rooted in consistency.

GM: What do growers need to know when upgrading their water filtration systems?

BP: Water filtration comes in a wide variety of options. The first step is to identify the objective. Does the grower only need to remove suspended solids? Or does the water need to have dissolved solids removed? The grower should be fully aware of the operation’s daily filtered water need and allow ample time for the equipment to meet that need. Some equipment may not have a 100% duty-cycle or require occasional maintenance. Furthermore, does the site have ample water pressure and flow to support the equipment, allowing for other water needs throughout the site which may impact the overall flow from the source? It can get complicated, very quickly. In short … the growers need a solid, workable plan.

GM: What are some common mistakes you’ve seen growers make with their water filtration?

BP: Some of the most common mistakes growers make include under-sizing their RO output based on the site’s incoming seasonal water temperatures. Not taking the temperatures into account can leave an otherwise properly sized RO underperforming for daily water needs. Other smaller mistakes include lack of general maintenance, not properly dialing in water filtration systems, or choosing NOT to have water filtration at all.

GM: What would you say to any grower hesitant about upgrading their water filtration systems?

BP: Equipment upgrades may include facility expansion, grow format change or a crop change requiring a modification in water chemistry. Considering the overall build investment, and cost potentials affiliated with a subpar harvest or equipment damage, the cost savings alone may outweigh the modest upgrade investment. Furthermore, water is a finite resource that should be professionally evaluated when choosing the proper filtration equipment for facilities of all sizes.