Growers Blog: Cleaning and Sterilizing

By cch2o

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The first step to any successful harvest begins in the preparation and planning stages. Controlled Environment Agriculture (CEA) allows the grower full control over every aspect of their plants growing environment. This includes providing a clean and sterile environment for optimal growing conditions. This sometimes overlooked step allows the grow room to operate at peak performance levels and is crucial to a successful harvest. Below you will find a step by step guide to cleaning and sterilizing the Under Current system.

Draining the System

The first step in cleaning the Under Current system is a complete system drain. This is important to rid the system of the previous nutrient solution, while also removing unwanted debris and giving the system an overall examination for any parts and/or accessories that may need attention. Draining the system can be done in one of two ways, utilizing the RETURN PUMP or through the DRAIN VALVE.


  • Turn off RETURN PUMP. Attach the GARDEN HOSE DRAIN ADAPTOR to the female side of a garden hose. Next remove the tee from the RETURN PUMP DIFFUSOR inside theEPICENTER and attach the GARDEN HOSE DRAIN ADAPTOR. Once end of garden hose is in desired drain location, turn on RETURN PUMP. Monitor water level as system drains, do not let RETURN PUMP run dry.


  • Remove cap from DRAIN VALVE. Attach female side of GARDEN HOSE to DRAIN VALVE. Run GARDEN HOSE to desired location (ideally a lower elevation than the DRAIN VALVE). Open DRAIN VALVE.

Note: The above methods will drain the system to within 1” in each module. If desired, remaining solution can be removed utilizing a wet vac or sump pump.

Cleaning and Sterilizing

It is important to clean and sterilize the Under Current system immediately after each harvest. This is to ensure any harmful pathogens, such as bacteria, fungi, and spores that may have been present are eliminated from the Under Current system. Utilizing Cultured Solutions UC Roots throughout the growing cycle will allow for an easier cleanup process. Chemical cleaners such as H2O2 and bleach are the most common and effective forms of sterilization. Other hydroponic specific products such as Physan 20 are also effective methods of sterilizing the Under Current system.

Note: Great care must be taken to ensure the system and parts are thoroughly rinsed and all chemical residue is removed before plants are returned to the system.

Sterilizing Chemical Ratios: 
H2O2: 35% grade at 3mls per gallon

Bleach: Unscented bleach at 1:100 ratio

  1. Drain the system using the above outlined methods.
  2. Remove and discard Air Stones: It is highly recommended to replace the Air Stones after each growing cycle.
  3. Remove any debris from the system utilizing a wet vac or sump pump.
  4. Use sterilizing solution to wipe down air hose, net pots and lids with green scrub pad or wash cloth.
  5. Sterilizing the system
    • H2O2 or bleach:
      • Fill system with tap water and sterilizing solution. Fill to the top of each bucket. Run the system for a minimum of 4-6 hours. Scrub system with green scrub pad.
  6. Scrub inside of joints utilizing a bottle brush
    1. Note: If bacteria was present during growing cycle, it is recommended to take apart both Return & Delivery Manifolds (on 3 or 4 row systems) and scrub thoroughly with chosen sterilization solution and bottle brush. On all other systems utilize a brush such as a chimney sweep to effectively reach and clean each manifold. It is also highly recommended to discard and replace all ¾” water hose.
  7. Rinse out the system with fresh water, while draining, until water runs clear and all residue is removed.
  8. Drain system completely and utilize wet-vac to remove any remaining solution.
  9. Wipe down system and all parts with clean towel and allow to air dry under HID lights and fans to aid in additional sterilization.

When executed the above procedures will provide the clean and sterile growing environment needed when growing in Controlled Environment Agriculture. Great care must be given to this step of the growing process, as this is the foundation that successful harvests are built upon. Every garden is different, figure out what works for you and your garden and plan accordingly.


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