# How to sterilize and disinfect your system



## mogie (Mar 21, 2007)

Sterilizing and maintaining clean conditions inside your hydroponics/aeroponics systems is extremely important. Keeping cloning, vegetative and flowering systems clean gives your plants a fighting chance against pythium (root rot) and other harmful diseases, ensuring healthy and vigorous crops. 

*Why?* 
Cleanliness is particularly important in closed (recirculating) hydroponic/aeroponic systems due to the favorable conditions these systems present to water and airborne diseases. Failure to periodically clean a system can result in stressed plants becoming infected and rapidly spreading disease throughout the entire system. Once infected, the entire crop will experience reduced vigor and yield. 

Prevention is the best cure for disease. Sterilization between crops, adding anti-pathogen additives, and attention to system design can help combat disease. 

*Materials:* 
· Hot water 
· 35% hydrogen peroxide (3% and 17% available at pharmacies, 35% at hydro stores). Oxidizes, then quickly (24 hrs) degrades to water (Sterilizing strength for 1-4 hours). 
· 99% Isopropyl (rubbing) alcohol. Kills bacteria and viruses on contact. 

Note: bleach is not recommended. It leaves a toxic residue. 

*Daily/weekly system maintenance:* 

_Daily:_ 

· Dip your portable ph/tds/temp tester(s) in Isopropyl alcohol, then rinse with water before testing solutions to minimize contamination between reservoirs. When taking a reading, submerge only the sterilized portion of the tester into the reservoir. 

· Periodically inspect roots for signs of pythium. Consider pulling any plants with these symptoms. 

Optional: 
· Add 1.5ml 35% h2o2/gallon. H2o2 can attack beneficial bacterial; H2o2 use is not recommended when using these enzymes. H2o2 at low concentrations can add beneficial oxygen to the reservoir without killing these enzyme additives. 

_Weekly:_ 

· Mist all tools, transfer buckets, etc with isopropanol alcohol in a spray bottle, then rinse with water before use. 

· Weekly or bi-weekly nutrient changes are recommended. (Go longer if using enzymes to maintain). 

· Remove and soak all pump filters/gaskets, thermometers, strainers, air stones, etc in strong h2o2 + hot water. 
· Wipe away salt and slime buildup 
· Add Guardian Angel or other pythium-inhibiting enzymes to tank (weaker h2o2 strengths are recommended when used in conjunction with these biological additives.) Maintain enzyme strengths. 

*System sterilization:* 

Note: 
Wear gloves when handling concentrated peroxide. Do not use bleach. 
Strong h2o2 will not burn off slime and salt buildup by itself. 

· Remove all plant matter from system 
· Pre-flush netcups/pots with water and inspect to ensure all roots have been removed. Put netcups/pots in dishwasher, then remove and soak in strong h2o2. 
· If infection was present, replace any grow medium; soak gro-rocks in strong h2o2 
· Recommended: remove and replace all irrigation. Biologically-resistant poly tubing is can be cleaned and re-used. 
· Soak all accessories in strong h2o2 (misters too, if possible) 

_system cleaning_ 

· Remove and sterilize reservoir by initally flushing with water and wiping with a clean cloth, then spraying 50% h2o2 with a spray bottle on all surfaces. Wait for one hour, then thouroughyl flush with water twice. 

· Flush system with water and do a pre-wipe (hot water + h2o2) to remove salt and slime buildup on all system surfaces. 
· Mix up a very strong (ie. 20%) H2o2 solution and spray it onto all system surfaces and allow to dry. 
· Run re-connected system with 10% h202 + hot water for several hours, dump, and flush again thoroughly with water. Dont plant right away! 

*General advice:* 

· Do not share tools and other equipment between systems or reservoirs. Isolating systems will contain any problems. Keep separate and dedicated transfer buckets, measuring cups, trays and other equipment; do not share between systems. 
· Keep your moms healthy and vigorous! Pythium will pass systemically to clones. 
· Inspect and remove unhealthy/slow growing plants early. 
· Use a pond strainer to keep leaves and debris out of tank 
· Tap water often contains elevated levels of chlorine to inhibit bacteria 

*System design considerations:* 

· Isolate systems with separate tanks, irrigation and pumps. 
· Use reflective surfaces (mylar, white poly or titanium paint) to keep the root zone cool between misting periods. 
· Keep system light-tight. Cover tank (but do not seal). 
· If possible, use low-cost UV / biologically resistant poly irrigation hose to minimize residue buildup. Pvc plumbing is difficult to inspect and clean. 
· Maintain nutrient temperatures in the 65-70F range for optimum growth and o2 saturation. 
· Maximize o2 levels in your system: waterfall-drop your nutrient return, use airstones/venturis/skimmers 
· Frequently circulate nutrient solution to avoid stagnant water.


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## Hemlock (May 25, 2009)

Man thats all cool but a little much...I know u have to do it


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## morrisgreenberg (May 25, 2009)

Hemlock said:


> Man thats all cool but a little much...I know u have to do it


 
yea but once you get going and you have your routine down pat, it becomes second nature, everything he just listed is exaclt what all successful hydro/aero grows go through, if you neglect just one aero(this is where they say soil is forgiveing) things get ugly fast...its a ton of stuff, still beats carrying 40lbs of dirt and flushing your soil it 1390724985 gallons of water


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## murtymaker (May 25, 2009)

subscribed... just for my notes! Thanks


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## Earl (Sep 3, 2009)

This is excellent advice, + rep
should be a sticky.
.


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## Muffy (Sep 3, 2009)

I use dish soap. Yeah, so clean you could eat off it.


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## RobMar (Sep 3, 2009)

Subscribed, thanks a lot. I'm getting in this routine. It definitely wont hurt.


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## MEANGREEN69 (Sep 4, 2009)

Earl said:


> This is excellent advice, + rep
> should be a sticky.
> .


i agree..very useful info thanks


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## marcoss (Dec 25, 2009)

thanks everything is really helpful. so what are the side effects of using bleach?


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## fatman7574 (Dec 26, 2009)

Of course you remove old roots and plant stalks etc. Duh! Then use a wet dry vacumn. Cover thermostats, and electrical outlets and pumps controls etc with taped plastic film and/or plastic bags as the vapor disinfectant/oxidizer will enter any and all openings and cracks. Followed by placing a small heat plate in the room with a small cheap soup pan. Pour about a 1/2 pint of 35% hydrogen peroxide in pot for a small room say 6 x 8 foot or less, (more for larger rooms), turn the control to high. Pull the electrical cord outside of room. Seal door cracks with tape. Plug in hot plate for about 10 minutes until you think all fluid is boiled away. 12 hours later remove tape. Do not go into room while there is any chance there is vapor still in the room. Use room. Pretty simple. 

When H2O2 is used in industry and medical facilities, labs etc they wear space suits (hazmat suits) and self contained breathing equipment and walk around with flash vaporizers, plus use stationary timed vaporizers. Two hours later they vent the room to outside and enter and wipe down metal fixtures/surfaces to prevent rusting.


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## Cpt. SeaWeed (Apr 21, 2010)

Perfect. I've been looking all over the web for this exact information and you nailed it. Thanks for the green info..


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## Dwight D. Schrute (Apr 21, 2010)

is it safe to run isopropyl alcohol through my water pump, mixed and diluted by water of course.


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## UrbanAerO (Apr 26, 2010)

I use a drop of dish soap and Ph balanced to water. I run this for 1 day every two weeks. Works amazingly and have even run it for 3 weeks straight for the first of flowering then they finished off amazing. Didn't hear anything about use of an ozone generator to sterilize your grow room and anything in it, between harvest. Alleged claims it to be more effective than wiping everything with alcohol and it only takes an hour, but cannot be used on live plants.


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