Before I make this statement, I will preface it by saying that I'm not refutting the possible benefits of using H2O2 (I use it myself) but I thought RIU readers might like to check out this article:
http://www.crophouse.co.nz/files/CG_W09-Hydrogen_peroxide-view.pdf
It's a pretty interesting article but the very first paragraph pretty much sums it up:
Hydrogen Peroxide is not suitible for root disease control in nutrient solutions of soilless cultures. This was the outcome of a research project funded by the VegFed Fresh Vegetable Sector reported in the Grower of october 2000. Pathogen control in water requires at least 100ppm of H2O2. Levels of 85-100ppm nearly killed young lettuce seedlings, while 8-12ppm reduced growth of hydroponic lettuce plants. H2O2 can be used, though, for disinfection of isolated batches of water or for making and keeping the irrigation system clean.
From another website:
http://www.greenhousecanada.com/content/view/1115/38/
Disinfection with Chemical Treatment H2O2 (Hydrogen peroxide)
First the Pros:
• Relatively inexpensive water disinfectant.
• No long-term or accumulative residues.
• Ideal environmental fate – breaks down into water and oxygen.
And the Cons:
• Relatively poor biocide.
• Sensitive to physical impurities.
• Heavy metals instantly catalyze H2O2 – cannot come in contact with metal parts, chelated micronutrients, etc.
• Interferes with micronutrients.
• Phytotoxicity issues at higher doses.
Two major cons which make me think twice about using H2O2:
Relatively poor biocide: In other words, you have to use extreme doses to kill pathogens, which in turn is a phytotoxic dose.
Interferes with micronutrients: This doesn't bode well at all.
So it seems, according to these studies at least, that in order for H2O2 to be truly effective at killing pathogens in your reservoir, it also has to be at a dose which is, at least somewhat, phytotoxic. Not only that, but it probably interferes with chelated micro nutrients as well. Are there any experienced growers here who have done a side by side comparison of H2O2 treated vs. non-treated nutrient solution and got any kind of meaningfull results?
I'm just curious, because while H2O2 treatment of nutrient solution is the conventional wisdom, I'm wondering if it's founded on a scientific/experiential basis or is it done just because everybody else does it?