# Bleach--more details



## slaytonp (Nov 14, 2004)

I found some more detailed information on the use of bleach as a disinfectant. Here I am quoting from the letters to the editor section of Microbe, June, 2006--The News Magazine of the American Society for Microbiology, vol 1 # 6.

This was from Norman Miner, MicroChem Laboratory, Euless, TX.

"Cecil H. and Michele H. Fox point out the disinfecting properties of inexpensive bleach (5% sodium hypochlorite) as an important germicide to help control the spread of influenza (or any other communicable virus, bacteria or fungus) (_Microbe_, April 2006, p. 159). A few more details might help for the effective use of diluted bleach as an antiseptic and disinfectant. Bleach is sold as a stable alkaline solution with a pH value of about 11 or 12. At this alkaline pH value, virtually all of the bleach is in the form of the chlorite ion (OCl-). At an acidic pH value of about 6.0 to 6.8, 90% of the bleach is in the form of hypochlorous acid (HOCl). Hypochlorous acid is 80 to 200 times more antimicrobial than the chlorite ion. Thus a simple formula to prepare an effective antimicrobial dilution of bleach is to add 2.0 oz of concentrated bleach to one gallon of tap water, and then add 2.0 oz of 5% distilled white cooking vinegar, also inexpensive and commonly available, to lower the pH of the bleach to about 6.0. This will yield about 800 ppm free available chlorine from hypochlorous acid. Use this acidified bleach in well-ventilated areas as there will be a mild odor of chlorine. The acidified bleach must be prepared fresh daily. Protect eyes and mucous membranes. Never add ammonia to bleach. Follow the safety directions as found on the bleach label. "

We discussed this some time back, but this gives more detailed reasons why the diluted bleach works better and also adds the acidification factor using vinegar. This might be a good one to put on a sticky or in permanent care sheet information. If there is some doubt about copyright infringement, I'm sure I can get permission to use this quotation from The American Society for Microbiology, or you can paraphrase facts given in the letter.


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## Guest (Jul 13, 2006)

Thats great info. I was recently (today actually) researching online how to best sterilze orchid seeds, and they all suggested bleach with a drop of detergent or to use Calcium hypochlorite I guess very similar to sodium hypochlorite.

Thanks Patty!!!


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## slaytonp (Nov 14, 2004)

I'm just guessing here, but I imagine the drop of detergent recommended for orchid seeds is for soponification, or breaking down any fatty, protective layers on the bacterial or fungus cell walls, making them even more reachable by the free chlorine. It sounds reasonable.


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## Guest (Jul 13, 2006)

Yup, thats what its about.


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## Guest (Jul 13, 2006)

I have used H2O2 with 95% success in disinfecting orchid seeds. Bleach was a big PITA because you have to keep rinsing the seeds with sterile water to get all of the salts out. And you can't keep the seeds in the bleach water for too long. The H2O2 worked much better for me.


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## c'est ma (Sep 11, 2004)

Oh, please, let's make this a sticky!


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## Guest (Jul 13, 2006)

mile, thanks, I was considering the H2O2. I think you convinced me. How effective is H2O2 on tanks though. I suppose hydrogen peroxide kills everything!


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## Guest (Jul 13, 2006)

I have no idea how effective it is on tanks. But I think it would have less negative effect over the long term than bleach because of the salt content in bleach. H2O2 would break down into water and oxygen. Maybe I'll go spray a couple of springtails and see what happens...

Back to orchid seeds... after soaking in H2)2 for a few hours (and venting the vessel every once in awhile), you have to put it in direct sunlight to decompose the remaining H2O2 before you put it in a flask. Otherwise it will play havoc with the agar.


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## Guest (Jul 13, 2006)

YOu put the seeds in for hours!!!! At what concentration of peroxide?


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## Guest (Jul 13, 2006)

100% peroxide. It's easier to do than bleach. Once you put the seed into a test tube, you just have to shake it up every once in awhile. You can leave the seed in there unharmed for a week or more. They are just sitting in plain water. Make sure you have some way to vent the vessel. Seriously. First time I tried it, I had rubber stoppers flying all over the place. Probably should have had on safety goggles. 

Leaving them in the H2O2 sol'n for a couple hours is probably mandatory as you want all of the H2O2 to degrade to H2O. I didn't do that one time and my agar all got lifted up off the bottom. PITA.


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## geckguy (Mar 8, 2004)

I believe you meant to say 3% solution, the stuff you get at any store? 100% hydrogen peroxide, is very unstable, and used as a rocket fuel. Even 35% hydrogen peroxide (commonly call food grade) is highly corrosive and can give nasty chemical burns.


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## Guest (Jul 13, 2006)

geckguy said:


> I believe you mean to say 3% solution, the stuff you get at any store? 100% hydrogen peroxide, is very unstable, and used as a rocket fuel. Even 35% hydrogen peroxide (commonly call food grade) is highly corrosive and can give nasty chemical burns.


Yes. That is what I meant. Hopefully khamul1of9 isn't off looking for 100% peroxide.


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## slaytonp (Nov 14, 2004)

There is also a 10% H2O2 solution available commercially, that used to be used for bleaching hair, (thus the old epithet, "peroxide blond.") That would seem too strong for sanitizing seeds, though. 

When one uses the chlorox bleach solution for sanitizing tanks before re-use, the tanks are going to be rinsed out afterwards with plain water, so I don't think residues of salts would be a big issue for this use. You can fill the entire tank with the solution and let it sit for awhile, then do some wiping and scrubbing of the glass, which is an essential part of cleaning anything. Physical removal of any deposits and organisms, as one does when washing one's hands or cleaning a counter, is an important part of any sanitation procedure. 

3% peroxide would be a pretty expensive alternative for a tank-cleaning purpose. It does not kill everything, since it is the release of concentrated oxygen that does the job, and this is most effective on anaerobes or facultative anaerobes, and it does damage tissue cells that have membranes, but at 3% concentration, it is relatively ineffective on parasite cysts and plant material with cell walls. So while it is probably safe and quite useful for sanitizing seed, it would not be as useful over-all for sanitizing a glass tank. 

Note that I'm still insisting that what we are attempting to do with either with orchid seeds or tanks is SANITIZING, not STERILIZING. These two terms tend to get used as synonyms, which they are not. (We old folk tend to be picky over definitions.) Surgical instruments and surrounding towels are "sterilized," but the patient's skin in the operative field is only sanitized, as he cannot be autoclaved for 30 minutes, just washed off with sanitizing chemicals to remove as many organisms as possible. We cannot sterilze a tank, unless we have access to an autoclave or something similar, and we don't want to do this anyway. We cannot "sterilize" seed without killing it along with the organisms we want to get rid of.


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## Jordan B (Oct 8, 2004)

Moved to Advanced Discussion.


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## Ed (Sep 19, 2004)

snip "mile, thanks, I was considering the H2O2. I think you convinced me. How effective is H2O2 on tanks though. I suppose hydrogen peroxide kills everything!"endsnip 

As Patty mentioned it does work well on anaerobes but it isn't that effective on aerobic bacteria and organisms as they contain an enzyme called catalase which pretty much renders it useless as a effective antimicrobial and antifungal agent (See http://en.wikipedia.org/wiki/Catalase for some info). 

I rountinely use bleach both as a sanitization agent and a sterilization agent. If you don't want to wait a long time to get rid of the bleach rinse the item in aquariun dechlorinator or a sodium thiosulphate solution. 

Ed


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## Guest (Jul 14, 2006)

milehigh said:


> geckguy said:
> 
> 
> > I believe you mean to say 3% solution, the stuff you get at any store? 100% hydrogen peroxide, is very unstable, and used as a rocket fuel. Even 35% hydrogen peroxide (commonly call food grade) is highly corrosive and can give nasty chemical burns.
> ...


I was about to say, even I wouldnt go near 100%, 35% laboratory grade is scary enough! 

Dechlorinator huh, thanks Ed!


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## Rain_Frog (Apr 27, 2004)

> I rountinely use bleach both as a sanitization agent and a sterilization agent. If you don't want to wait a long time to get rid of the bleach rinse the item in aquariun dechlorinator or a sodium thiosulphate solution.


I have adopted this practice after talking to ed privately. Generally, I rinse every bucket from frog water or changing of substrate with a mild bleach solution, rinse a few times, and add chlorine remover to the bucket. Rinse again, and let dry in the sun.


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