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Biofilms: What They Are and What You Can Do About Them

June 28, 2016

A major threat in either hydroponics, soil or organic-based media is the biofilm, which is composed of microorganisms. A biofilm can carry pathogens that can infect not only your plants but can disperse throughout a professional grower’s entire system.

When microscopic lifeforms aggregate, their cells stick to one another. As trillions of these cells collect in a hydroponics system, they create a massive colony (biofilm) that appears as a greasy, slimy film. Biofilms are dangerous to grows because they invite disease-causing agents that can harm or kill plants. Some biofilms carry pathogens that can infect humans.

One of the most common biofilms is caused by algae. If you’ve ever managed a hydroponics system, you’ve probably encountered some algae. It’s easy to spot algae biofilm, because it’s typically green and brown from dead chlorophyll. Other biofilms, however, aren’t so obvious.

Removing biofilm in hydroponics systems

Because most biofilms proliferate invisibly, you should always clean out your hydroponics systems at least twice a year or whenever there’s an outbreak of a disease or pest. This means a complete shutdown of the system while cleaning takes place.

  • First, good old-fashioned scrubbing will do more to clean out biofilm than anything else. This physically scrapes up and isolates the biofilm from the grow area. Be sure to properly dispose of the waste; that is., don’t just pour the waste back into your watering system.
  • Second, to get rid of biofilm in the pipes and other difficult-to-reach areas, use an acidic solution. The acid will dissolve the biofilm into a thin liquid, allowing it easily wash away.
  • Third, keeping the grow area sanitized on a regular basis can keep biofilm from forming at all. Hydrogen peroxide, bleach and ethanol solutions are simple ways to control the problem. Be sure you’re using the correct concentrations so that you don’t hurt young plants.

Water treatment options will also keep biofilms from accumulating. Reverse osmosis, UV treatment and slow-sand filtration are all effective. Just remember that tap water, although treated for human consumption, may still contain pathogens that threaten a grow. Taking the extra steps to keep the water clean will save you a lot of headaches further down the road.

Removing biofilm in soil and organic media

Pathogenic biofilms can proliferate in soil, too. These aren’t easily spotted, and you may need a microscope. Test meters, strips and other visual cues may give you telltale signs.

The best way to prevent harmful biofilm buildup in soil or husk is to keep it from ever taking hold. To do this, add compost tea to your medium. Compost tea introduces beneficial microorganisms that generate good biofilms. Infectious ones can’t compete, and the good biofilms stay in place.

If you do happen to get bad biofilm in your media, use soil treatment solutions or replace the contaminated media with new media. Earthworms may possibly be the most affordable and effective way to clear out disadvantageous biofilm from organic media.

Don’t get lazy or crazy

Improper disinfection can also worsen the situation. If you fail to remove the biofilm, the colony will defend itself by reproducing faster than ever. This can quickly exacerbate your problems with biofilm infections.

Furthermore, be careful not to go on a microbial killing spree in a hydroponics system. Only the biofilm needs to be removed with a little disinfecting to keep spores and bacteria from taking hold. A full-on “nuking” of the grow area with disinfectants will also kill the beneficial microbes needed to keep your grow environment healthy. Solutions with too much hydrogen peroxide or bleach can poison the plants, so take it easy and practice hygiene in moderation.

By Randy Robinson
Image Credit: By Alexander Klepnev (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons
Cannabis Cultivation Today articles are for informational purposes only and should not be considered legal guidance or advice on grow practices. You should contact an attorney or a qualified cultivation consultant for specific compliance and cultivation advice.



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