Correct use of H2O2 for hydroponic root rot

It was recommended that I soak my roots in H2O2 solution for an hour to help with my hydroponic root rot. I only have access right now to otc Peroxide at 3% solution. I have found so many variations on instructions for use. So here’s my basic need… Is 1 part h202 3% to 4 parts water the correct thing to do?

I don’t know but that sounds awful strong ?

hold on before you do anything let’s see if we can get a hydro guy opinion … I invited a couple here, if I were you I’d hold on

  • best of luck!

hiya …if I recall, 3% H2O2 dosage, 5ml to 10 ml per gallon…start low and increase, a dose a day over three days.

I have seen much higher percentages for an hour soak but WAIT for more advice please

here’s a link from @Donaldj

Using Hydrogen Peroxide in your Hydroponic Garden - Step by Step Hydroponics

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Thanks for the link…Read it. I am hoping to be able to soak the net pot, clay, and roots for the hour, rinse everything, and put back into new solution. Is this realistic?

yes, but not at a one to four dose rate…if you are going to soak, include the clay balls, it would be easy to leave the solution too low and still have unwanted micro-organisms living above the water line.

there are folks that use H2O2 regularly thru their grow with no problems.
the negative is that there are beneficial things that get killed by the soaks and they are important for nutrients.

Yeah that’s way too strong

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sorry for the intermittent replies, it’s a babysitting weekend for us.

I had root rot, called a 1-800 phone number the nutrient line I was using had.
the person on the other end recommended 30 ml (3%) per gallon for a one hour soak, up to 150 ml in the bucket…
I did 75 ml in my reservoir, which was not the answer to my problem. The rot persisted so Either H2O2 isn’t the best way to kill rot OR you need a stronger dose. I can not recommend the stronger dose never having done it.

I started to watch the video and it looks very informational…thanks @Paranorman ! especially all the chemical names available to help control it.
I hope not to have to watch it based on “need”

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Yeah a lot of info but I still don’t know the answer to this question except that I believe the what was it, 1 to 5 ratio op mentioned up top was too strong …I bet @Donaldj knows !

Well you can’t really over do it with a 3% solution but with a 29% you’d want to be careful and once you start using h2o2 be committed to using it all the time since good bacteria is killed too so their is a void that any bacteria will want to occupy. If you are using organic nutes you can’t use it and many product lines use bacteria to aide in chelation also what does survive is made stronger and given less competition. The best way to control bacteria is to use good bacteria and or keep res temps fairly low 68f or so. I do like h2o2 but you need to use it constantly once you start using it


Thanks to everyone for the assist. Seems my answer is H2O2 3%, 30 ml/gal for 1 hour soak. From what I am learning, I probably will be better off with the beneficial microbes once I get the rot under control, mainly because of my high air and water temps at around 80-82. Last night, gave 60 cc h2o2 in 4 gal nutrients. This morning the water is cleared up, still some brown to the roots, but is improved. The best I can guess, I will wait another 24 hours, redose with same h2o2 60cc. Then introduce microbes after 3-4 days. Thanks again to all.

I just want to say how very pleased this blog has made my search… thank you all…I am going with the 3% 3ml/gal…see what happens … they have shrunk a bit … but love has no boundaries wanting to make them well, and find a reason… Thanks to all your experience.

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When I ran a sterile res I would add 15 cc/ gal every 3 days

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So will beneficial bacteria prevent root rot all together? Or does it greatly reduce the possibility?

Won’t prevent it but does kill off the microbes in res. Some growers will kill off everything, then add them back in with a product like hydroguard or terpinator. If your roots get too warm they struggle with oxygen absorption leading to all other problems it has.


i heard something completely different… add to the solution 2-5ml per gallon and it conditions the roots and prevents root rot. iddunno if thats true or not. but thats what a experienced grower was recommended and he was trying it out so im assuming it might work? idunno. just use botanicare hydroguad so you have no root disease sounds like a better plan imo!