[JLudwig]

hydrogen peroxide is used for spot algae control. I think its the increased oxygen that kills the algae. I don't think hydrogen peroxide is that great for plants. Your best bet with algae is getting the plants to grow well.

Then why doesn't O2 or ozone work or just straight up H2O2 to the water column? This is still a big mystery to me... current thinking by "experts":

- Plants don't 'outcompete' algae, so it isn't nutrient limitation.
- Plants might produce excess O2/high redox which kills algae, but then H2O2, O2 or ozone should work
- Alleleopathy, but not with our huge water changes, shady science here, etc, etc...

So we have no idea, other than the satisifying Zen gardening principle of "Focus on growing plants not on preventing algae...."

btw- in terms of this even being effective in ponds, I've seen several "credible-looking" studies that disputed this, but I could not find anything peer reviewed.

Jeff

 

[JLudwig]

I'm thinking if lower level plants such as algae are more sensitive to this form of O.

Okay, so... add ozone, it decomposes through a radical route, so does peroxide. Why doesn't dosing peroxide/ozone directly to a tank help?

This is all terrible pseudo-science at best, especially the cosmetic example you give. Its fine to hypothesize but the next step is to test your hypothesis, or at least give me a reference to something peer reviewed... You could setup two small tanks, introduce plants and algae to both at the same levels dose one with peroxide, don't dose peroxide for the other, take pictures as the weeks go on. But until someone does this experiment it senseless to talk about radicals beating back algae.

A non-pseudoscience prediction is that radicals will readily oxidize any organic matter in your water column, such as tannins, organic matter and the chelating agent holding your iron in the proper oxidation state... you can find this in any water treatment handbook.

Jeff

 

[JLudwig]

Yes it does. Most folks aren't dosing enough, and thank goodness they don't because it's not at all safe for fauna.

Well, by this standard bleach also is an effective algae control reagent. If peroxides are needed at levels that are harmful to fish to suppress algae, I really doubt plants/or barely straw are using this mechanism... Let me rephase, why can't I dose small non-lethal levels of H2O2 or ozone to suppress algae? If you have direct evidence for this in a controlled experiment, I'll be more than happy to change my views.

I should explain why I'm being a bit of a pill here... There is a lot of unsubstaniated scientific nonsense in this hobby, and I aggressively go after people who promote these viewpoints. The current truth of the situation is that there is no viable and tested explanation for why a bunch of plant growing happily keep algae from appearing. This point is not made enough, and it is something everyone new to the hobby should know. This fact encourages experimentation and exploration of variables/new techniques and creative DIY alternatives. Stuff such as "O radicals inhibit algae growth" sends people down the wrong road of experimentation, for example my hypothetical technique of peroxide dosing.

Advancing a viewpoint such as oxygen free radicals (this one is a pet peeve of mine, sorry) inhibiting algae growth, stated as a matter-of-fact without any experimental confirmation is not only bad science, but irresponsible. Its this know-it-all attitude that kept me on a cookbook approach for way too long and really held back my success as it kept me from experimenting on my own, thinking the whole time I was doing something wrong within the technique. There is no answer, and at the end of the day, "Focus on meeting plant needs" is much better science than SWAGs about root causes of algae inhibition. Barley straw, until tested experimentally by a third party in a controlled experiment, is bad science and nothing more can be said about it right now.

Jeff