Date:         Fri, 3 Aug 2001 09:39:24 -0700
Reply-To:     The River Clan <staff@EARTHNOW.ORG>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         The River Clan <staff@EARTHNOW.ORG>
Subject:      Re: Safe way to clean Westy water tank?
In-Reply-To:  <032501c11777$68253320$9751c0d8@mydomain>
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Wow! That's more info than I can fathom!! Are you a chemist? = )

What about using Food Grade Hydrogen Peroxide?



At 11:09 AM 7/28/2001 -0400, you wrote:
>> My water tank is pretty slimy (haven't used in
>> awhile) and I'm looking for something to clean
>> it with that won't poison me after I refill it.
>> Any suggestions?
>
>Actually there is no safe way to do this.  If you do not feel comfortable
>doing this, then do not.
>
>For this type of disinfection, maintaining the chlorine level at 1000 ppm
>for 20-30 minutes will kill everything in the tank, sterilizing it.  To get
>to this level with our 10 gallon tank and using household bleach
>(5.25%)which is 52500 ppm, you need to add approximately 24.5 oz of bleach,
>about 3 cups, to the tank and fill the tank.
>
>{Conc of bleach * oz of bleach} + {conc of bleach in fresh water * (oz of
>fresh water - oz of bleach)} = {Final conc * total volume}
>
>{52500 ppmCL  *  (X oz)} + {0 ppm CL * (1280 oz  -  X oz)}  =  {1000 ppm CL
>*  1280 oz}
>
>Solve for X which is oz of bleach.  In this case 24.38 oz of bleach
>
>We run some of this solution through the pump to sterilize the pump and
>piping to the sink,  a minute or so.  Then we drive around for the 20 to 30
>minutes.  The contact time of the chlorine mixture with all surfaces is
>CRITICAL.  Do not skimp on this time!  It is equally important to flush the
>entire system with a large quantity of known clean water, as chlorine is
>corrosive and if left in the tank or pump will do damage at these high
>concentrations.  Do not forget to flush the pump and the piping to the sink.
>
>After many of these treatments you may damage the pump, I do not know if the
>pump materials are chlorine resistant.  But it is cheap as compared to a
>ruined trip and a trip to the hospital.
>
>If you have a lot of green growies, flush them out as best you can.
>Chlorine when combined with organic material can make trihalomethanes, which
>are known carcinogens.  If you can not flush these out, do not worry.
>Remember you are not going to drink this stuff.  This is just to kill
>everything in the tank.  You are going to flush the bejeezus out of the tank
>with clean water.
>
>
>Be careful of your eyes and clothing and upholstery when adding the bleach
>to the tank.  I remove the top of the tank from inside the van to add the
>bleach.
>
>
>
>
>
>BTW 1mg/l is 1 ppm,  so 1000 mg/l is 1000 ppm
>
>
>This is some info on chlorine for disinfecion:
>
>Reactivity of Chlorine Compounds
>
>Chlorine was first discovered to be a disinfectant in 1787 and has been
>universally accepted and utilized ever since. The reactivity of chlorine has
>been well studied and general guide lines for its use are as follows:
>
>Inorganics: Chlorine, used by itself, requires a concentration of 6 mg/L per
>1.0 mg/L of inorganic at a pH of 8.5 -9.0. If used in conjunction with
>permanganate this ratio will drop to below 1.0 mg/L per 1.0 mg/L of
>inorganic but will require tight instrumentation controls.
>
>Pathogens: At a pH of 4-5, chlorine is effective as a disinfectant when used
>at a ratio of 1-3 mg/L per 0.5 mg/L pathogen and requires a residence time
>of 45 - 60 minutes (12 time that for Ozone).
>
>Pathogens: A 500 mg/L chlorine concentration will normally be effective
>against vegetative bacteria. At this concentration, chlorine has limited
>effect against viruses and is poorly effective against bacterial spores and
>fungi (adverse effects on body chemistry/metabolism).
>
>Pathogens: a 1000 mg/L chlorine concentration is effective against all
>bacteria, viruses and fungi yet requires 25-30 minute residence time
>(adverse effects on body chemistry/metabolism).
>
>Organics: practical applications of chlorine, even at 1000 mg/L have little
>effect on oxidizing organic material other than generating chlorinated
>organics, hence chlorine is not recommended for this use.
>
>Residual: A chlorine residual can be provided only after the demand for
>chlorine by inorganic, bacteria and organics has been met.
>
>Chlorine can be effective for oxidizing inorganics and bacteria when pH,
>concentration and residence time are allowed for, but the chlorinated
>organic by-products are inevitable and only some may be filtered out. For
>agriculture applications, the important consideration for utilizing chlorine
>compounds is the amount of chlorides that will end up being consumed by an
>animal, the impact of the chlorinated organics on the animals' performance
>and toxic residues absorbed into the tissues of the animal.. If excess
>chlorides are produced, necessary steps should be taken to remove them as a
>last step in a water treatment program.