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Re: [APD] Bleach sterilisation

Richard J. Sexton wrote:
>>Excel is not intended to, not is it likely to be a thorough algacide. I've
> heard all kinds of wonderful reports on the incredible things excel does
> beyond what the maker claims. I doubt all of it except what Dr. Morin has
> confirmed -- iirc, promotes plant growth, slighlty antibacterial. Insofar as
> it promotes plant growth, it can indireftly prevent algae outburts.  I've
> heard of folks adding excel and witnessing an algae die-off. I've also seen
> excel added without any algae die-off.
> You're not asking Dr. Morin the right questions.
> He will not say it kills algae. He can't, by law. To be an "algicide" it has
> to go through FDA testing
> which is a 6 to 7 figure deal. So, according to the US govt Excel is not an
> algicide.
> But, if you ask Dr. Morin if Excel works for "moss balls" (Cladophora algae)
> he'll tell you
> they do poorly and die if you use excel.
> While I have seen one or two andecdoral cases of excel not killing algae
> (frankly in some
> pretty suspect tanks) the overwhelming majority report that if kills algae.
> I spent years messing with bleach and peroxide to kill algae. They work but
> the side effects
> are poor to disasterous.
> Bleach - pro: it killls algae outright. 4-7 minutes diluted 1:20. Con: half
> the plant
> may die and it may take a month to get going again. Anubias seem to be badly
> affected by
> it. Any existing leaves die off and given the rate of growth of this plant
> it is to me
> a non starter. Crypts don't fare as badly but do take much longer than
> normal to get
> growing again. I've never used it on stem plants, buying new ones is just
> too easy. I
> spent about 3 years messing with this stuff to no good end really. By the
> time the 
> plant had revovered from the bleach the algae had grown back by that point.
> The secret
> is t
> Peroxide - pro: kills algae. Con: and everything else. There may be a sweet spot
> where it kills only algae but I looked for a year for this and never found
> it. It
> must be a very very fine line. H202 is superb at killing the good bacteria in
> your tank and is absolute death on certain plants.

At concentrations below 16 mg/L H2O2 does not have any deleterious 
effect on bacteria that I can measure. There was a study done about 
using H2O2 in water mains to prevent biofilms and they couldn't kill the 
bacteria under 16 mg/L.

H2O2 has some other benefits, like oxidizing organic compounds. 
Unfortunately it does oxidize iron as well (Fenton's Reaction), so if 
you have some in your water you will get a whitish haze for a couple of 

Jerry Baker
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