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From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Cleaning gray tank
Date: Fri, 04 Aug 2000 05:58:11 -0400

Stan Birch wrote:

> Chris,
> >Between the Tide and bleach, whatever had been
> >>messing up the sensors had been dissolved, disintegrated or whatever.
> >>I think the bleach was the primary active ingredient.
> >On Thu, 03 Aug 2000 Chris Bryant <> wrote:
> >       But... the bleach is a big no-no. It will destroy the seals in
> >the drain valves, as well as the toilet (albeit more slowly).
> It is well known that petroleum distillates will damage some rubber
> compounds, other than perhaps neoprene, but I would like to see
> credible proof that bleach has any adverse effects on rubber---I don't
> believe it does.
> The rubber drain-hose on our washing machine at home has been pumping
> out bleach for the last 25 years, and is still going strong.

Yo Stan.  Little secret that may not have worked its way up to
Ehland yet.  Different rubbers are vulnerable to different

Another secret - the rubber used in toilet seals (probably butyl
rubber) isn't compatible with chlorine bleach.  Chris told you that
from experience.  I tell you that both from experience in having our
hyperchlorinated drinking water eat the diaphragm out of my tankless
water heater every 6 months or so, and by understanding the
chemistry involved.  I have no doubt that this isn't sufficient
"credible proof" in your book but it probably will work for everyone
else.  And if you want to bleach out your holding tank, well, a
blown gasket couldn't happen to a more deserving person.  IMHO, of

> And if bleach damages rubber, why would Dicor recommend it for
> cleaning rubber RV roofs? They say:

because a rubber roof is typically UV inhibited EDPM which is highly
resistant to oxidation from elemental oxidants.  Sunlight creates
ozone which decomposes to atomic oxygen and O2.  The atomic oxygen
is what damages the rubber and what is inhibited against.  Bleach
acts by releasing atomic oxygen (along with atomic chlorine) when
the hypochlorite decomposes.  Ergo, bleach is no more harmful to
this particular rubber than sunlight.

BTW, the bleach that goes down the drain in your washing machine is
very dilute and what is there is pretty well spent.  Your drain hose
is probably neoprene which is resistant.  And if you look in your
hose, you'll see a protective film of soap scum on the inner

Bleach shouldn't even be in this discussion in the first place.  It
has NO cleaning effect.  It simply bleaches and sanitizes (kills
germs). Sanitation has little meaning in this context unless one
plans to work on the sewer system. And unless it is mixed with
laundry detergent, it is killed by detergent additives upon mixing.

The bacteria/enzyme approach is about the only one that will work
with the "pour'n'pray" technique.  I choose to neither reward
RVchem's scare tactics nor pay their price so I buy the very same
bacteria from the hardware store in the form of RoeBic K-67
Bacterial Drain & Trap Cleaner.  Actually most of the reputable
brands of bacteria products contain the same stuff - there isn't a
lot of biodiversity in the grease eating bacteria field.  A quick
check of the product's MSDS will show the particular ingredients.

While I'm on the topic, the boasts about how many bazillion bacteria
are in a particular product are pretty much BS.  Since bacteria
multiply geometrically, the only effect of having fewer bacteria is
that it takes a few more generations for the bacteria to multiply to
useful quantities in the blackwater tank.  Since we're talking only
minutes to a few hours, depending on temperature, the initial
concentration is fairly irrelevant.

> Just because some snake oil says "RV" on the bottle, doesn't mean that
> it won't cause severe damage to your RV.  For instance, if I recall
> correctly,  Protect-All was pedalling rubber roof cleaner for RVs,
> knowing full well that it would destroy the roof because it contained
> petroleum distillates. They maintained that the fact,  that just
> because it caused the rubber to swell, that it wouldn't really hurt
> the roof. That was blatant fraud on their part.

I'm sure you believe that this has some relevance to cleaning a
holding tank but it escapes me.

> And when RVchem claims that bleach has a degenerating effect on the
> valves, hoses, fittings and tanks used in **SOME** RV and marine
> holding tank applications, they are not very specific; but bleach is
> not going to do any damage to any modern RV with system typically
> constructed of polyethylene, ABS plastic, neoprene, and stainless
> steel components.

What, you expect RVchem to provide an exhaustive list of RVs damaged
by bleach?  Absurd.  Of all the wild claims they make, this is the
nearest to the truth.

> If it works, fine---I don't have a problem with that. The use of
> enzymes can be the most effective way  to accelerate biochemical
> processes and break down organic matter. That's why enzymes are so
> often used in laundry detergents. So what you use, is a compromise
> between effectiveness, economics and availability.

Apples and oranges.  The enzymes in laundry detergents are protein
specific, designed to break down the proteins that bind blood and
food stains to clothing.  The bacteria used in drain cleaner
products is a mix of several different engineered bacteria that
primarily digest grease.  They produce the enzymes that break down
grease and other organic material - the difference is the bacteria
multiply and grow until the food (grease) is consumed or some bozo
decides to help 'em out with a little bleach and kills 'em all off.

Finally, I find it amazing that you'd challenge a pro like Chris
with no more evidence than a hope and a guess.  I'm fairly sure he's
forgotten more than you know about RVs.  I'm positive he does on
this topic.


From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Cleaning gray tank
Date: Sat, 05 Aug 2000 21:10:29 -0400

Stan Birch wrote:
> >> The rubber drain-hose on our washing machine at home has been pumping
> >> out bleach for the last 25 years, and is still going strong.
> On Fri, 04 Aug 2000 Neon John <> wrote:
> >Yo Stan.  Little secret that may not have worked its way up to
> >Ehland yet.  Different rubbers are vulnerable to different
> >chemicals.
> >
> >Another secret - the rubber used in toilet seals (probably butyl
> >rubber) isn't compatible with chlorine bleach.
> You have a rather low view of engineering efforts on the part of the
> RV industry---and perhaps rightly so.  But to pick at random butyl
> rubber as a probability is really reaching.

No random pick, stan.  That's what the replacement gasket feels and
smells like.  Might also be Buna-N.  Not worth the effort to figure

> The most commonly used
> material for O rings is a fluorelastomer marketed by DuPont-Dow under
> the Viton trademark, which offers exceptional resistance to chemical
> degradation, including oxygenators.

Ah, no.  The garden variety O-ring is Buna-N.  That's what you get
at the hardware store and what is used in most ordinary
applications.  Viton is a high end product - the O-rings I use on my
high vacuum system are Viton and cost almost a buck a pop, more if I
buy the pre-degassed ones.  Only place I've seen viton on
automotive-relatd stuff is on refrigerant connections.  The extra
cost of viton simply isn't worth it for most applications.


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