We have all seen the symptoms of native, established biofilm. Clogged drippers or emitters. Clogged filters. Increase in pathogens. Reduced water flow. So, how do we treat a biofilm to decontaminate and stabilize your irrigation system?

To understand the treatment process, we need to understand microbial biofilms and how they form. Biofilm starts with aerobic bacteria. As aerobic bacteria accumulate in your system, they begin to adhere and “recruit” other microbes to build a community of single-celled microbes. The attachment phase of bacteria can take seconds to minutes. Once bacteria are attached, they begin growing. This phase can take hours or days to perform, depending on your system’s environment. The more accommodating, the faster they will grow. Once the bacteria are established, they begin polymer production to “recruit” other microbes into their growing community. The polymer production phase begins the final stage of biofilm growth: attachment of other organisms to biofilm. In this stage, algae, molds, yeasts, and coliforms can begin flourishing in their new neighborhood. Available minerals, such as iron and calcium, help protect the inner working layer of the biofilm. The biofilm matrix’s growth is proliferated by the availability of nutrients. Nutrients diffuse into the matrix as they flow by. The bacteria produce a slime that helps protect the entire matrix. Think of the biofilm matrix as growing in 4 or 5 layers, with the innermost layer being the most active for growth and the outer layers providing protection. This entire community, basically, is acting to proliferate and spread throughout your system. Everything within the matrix serves a purpose, and the organisms do work together to survive and thrive.

Now that we have established the complexities of a biofilm matrix let’s get to discussing how to eradicate them. We recommend a 2-step “line shock” to eradicate native, established biofilm. This process is not plant friendly, so it is best suited as part of your between crop clean-out. I would argue that it is an integral part of your between crop clean-out process because the biofilm matrix is harboring plant pathogens, so your irrigation water is now potentially delivering water-borne pathogens to your crop.

The first step in decontaminating your system is to utilize an acid-based detergent such as GreenClean Acid Cleaner. The acid cleaner will lower the pH of your water down to about 3. We perform this step with a Dosatron injector capable of injecting at 1:100. This is low enough to solubilize those mineral deposits that are part of the biofilm’s defense system. The detergents in the cleaner also create crevices in the biofilm layers that will be advantageous to the follow-up disinfectant. Let the acid cleaner sit for 1 - 2 hours, then flush out with fresh water. The next step is to inject a disinfectant such as SaniDate 5.0 to kill the now exposed, inner working layers of the biofilm. We inject SaniDate 5.0 with a Dosatron injector capable of injecting at 1:100, filling the system entirely and letting that solution sit. I recommend at least 3 hours for this step, but 8-10 hours is optimal. Flush out the solution with fresh water. When flushing out Step 1 and Step 2, make sure to flush out through a larger orifice such as a flush valve. The dead biofilm still has biomass and will not easily flow through drippers/micro-emitters.

For more information on Biofilms and/or Irrigation Line Cleaning, please feel free to contact BioSafe Systems at 1-888-273-3088 and request our Line Cleaning Programs. You can also reach me on Instagram at biosafe.indoorgro. Dosatron injectors are trusted by BioSafe to deliver our chemistries precisely. Please contact Dosatron directly at 1-800-523-8499 to request more information on their injectors.

Jeff Kline