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Scott730 · 08-11-2009, 07:29

Highseas
You need to backflush a watermaker with fresh water to clean it out after making water. So you do recieve water from the tanks for this purpose. That is way Spectra includes a filter to remove the clorine/bleach before it enters the system for back flushing. However, I'd rather not depend on the filter to keep clorine out. We also place some of our RO water in plastic jugs just for drinking so we are not drinking out of the tanks. Still would like to keep the tanks clear without using harsh chemicals.

aboutgone · 22-11-2009, 06:06

here's some info on h2o2....http://inspectapedia.com/water/Drink...ification5.htm

Mark Zarley · 22-11-2009, 12:52

Using bleach or peroxide to sanitize your entire system is only the beginning. To keep it clean we only fill our watertanks with "city water" that has been treated. Lots of marinas use wells for a water source saving on city water and sewer fees. The down side to this is the water gets funky when men repair leaks or add onto the line. This includes blowing out the lines with compressed air in the fall for freeze protection. I have never seen a marina "shock" their water system. Another down side to untreated well water is sediment,and of course this will settle out in your tanks and flow out of your fawcet after a "rough ride". Another source of contamination is the dockside fill hose, think dog owner letting his best friend take a drink. We know of one couple who swab the dock hose bib before hooking up their own carefully protected hose. Unfortunatly they forgot to drain the hose after a fill up and the next time a big old slug of green slime shot out the end as they purged the line prior to fill up(that last fill up wasn't as pure as they hoped). We on the other hand prefer to make our own water. Keeping the tanks clean is no problem as the membranes in the water maker are very fine filters (compare the size of a molecule of salt to a microorganism, the later is huge). To sum up ,start out with clean tanks and then add only treated or watermaker water. This works for us.

Shack · 21-03-2010, 13:41

Quote:

Originally Posted by Scott730

If peroxide is used, what is the ratio per gallon of water? How long do you leave it in the system and do you flush it with a full tank of water?

Scott730,
I see that you asked this question twice and got no response from anyone. I have the same question. Did you ever find an asnwer for treating a tank? (ratio per gallon and sitting time).

I could assume to use the same ratio and sit time for bleach, but ...its not bleach and it may be a bad assumption.
Thanks,
Shack

UPDATE - UPDATE

I kept searching and found this on another thread.
"If using the 35% peroxide use 1/10 gal per 100-gals of water. But if you want to there isn't anything wrong with adding a higher amount. If using something weaker just ratio it out."

Still unsure on sitting time, but I will try it for a few hours and flush it.

Thanks,
Shack

Scott730 · 21-03-2010, 13:59

Shack
Still have not gotten an answer to my question, starting to wonder if anyone really has used peroxide to treat their tanks. A lot of talk but still no specifics. I think I'll stick to something I know works and use bleach.

S/V Illusion · 21-03-2010, 14:29

Quote:

Originally Posted by Scott730

Shack
Still have not gotten an answer to my question, starting to wonder if anyone really has used peroxide to treat their tanks. A lot of talk but still no specifics. I think I'll stick to something I know works and use bleach.

Bleach may be simpler but not as effective nor does it have the residence time peroxide has. The reason you haven't received an answer is probably because it depends entirely upon what concentration peroxide you are using. Feel free to send me a private message with that info and I'll tell you how to calculate the proper mixing rate.

FYI - it's not a simple "plug-in" formula which is why we can't give you a generic answer.

Scott730 · 21-03-2010, 14:38

Illusion
No reason not to share your thoughts with all on this subject. I have a 3% solution, how much would you add to 50 gallons?

Thanks
Scott

Bill_E · 21-03-2010, 15:28

I've been worried about the same issues but haven't tried to get to the bottom of it until just now. Here are a few factoids and a link. We used to use hydrogen peroxide (H2O2) in bacteriocide research. One relevant thing is that it is the product of time and concentration that seems important. In other words, a weak concentration for a long time or a high concentration for a short time. One problem with H2O2 is that it is intrinsically unstable so will become more dilute with time. It is also very reactive with certain "things". It will react with some metals, in particular, iron and copper, It will also react with organic pollutants, even those that are benign, like the humic material in most water. And, it reacts with hypochlorous ion, the chlorine form of bleach and most chlorinated city water systems.

Having said that, hydrogen peroxide is an excellent biocide and (as noted) has the advantage of not producing any nasty products. If left alone it will decompose to water and oxygen. In use, the products are oxidized organics and water. It disrupts several biological processes in bacteria notably damaging the cell walls.

I found the following website that has information on H2O2 disinfection, 35% hydrogen peroxide It looks to me like they recommend 0.025% of 35% H2O2 to "shock" a hot tub system. That is about 1 cup per 250 gallons. On the other hand using too much won't hurt your system though it may cost a bit more.

I think that what I'd do is to flush my system well and fill my tanks with city water and then wait a couple of days. The "chlorine" in the city water should evaporate slowly and then add about a cup of 35% H2O2 per hundred gallons or so, wait a few hours for mixing to take place in the tank, and run it into all of the lines. That is open the faucets and drain out enough to get the hydrogen peroxide into all of the nooks and crannies of the lines. Then top off the tank. Then wait at least 24 hours before draining, if desired. I'm not sure if you have to drain the system. In a day or so, the peroxide level should be low enough to be OK for drinking.

Better yet, use a carbon filter on your hose when filling the tanks then you will probably get most of the organics out of the water as well as the "chlorine". I think I'll look for a simple carbon filter to use on my hose when filling my tanks anyway.

Hypochlorite (bleach) is corrosive to most metal tanks. It is just that it reacts a lot faster with aluminum. So, a carbon filter is probably a good idea if you have aluminum tanks because city water probably contains at least some hypochlorite. Hydrogen peroxide does not react with aluminum.

I hope that this helps a little. Now to put it to use myself.

Bill

S/V Illusion · 21-03-2010, 16:04

Quote:

Originally Posted by Scott730

Illusion
No reason not to share your thoughts with all on this subject. I have a 3% solution, how much would you add to 50 gallons?

Thanks
Scott

Scott
That's the problem. I'm sure you appreiate that the answer you are looking for depends on concentration and with the typical 3% drug store type peroxide, you are wasting your time and money. I could povide a formula but it is misleading since the chemistry requires a baume concentration which isn't directly extrapolated from the % concentration you and others often quote.

Drug store peroxide with dilute to essentially nothing upon contact making it innefective.
Let's start with a more important question since we're wasting our time if you cannot obtain a higher concentration peroxide - do you or can you find a local supplier of a 30%+ concentration?

Scott730 · 21-03-2010, 16:06

wlearl
Thanks for this info, it is exactly what I was looking for.

Scott

S/V Illusion · 21-03-2010, 16:30

glad to have taken the time trying to help

Stevens 47 · 21-03-2010, 17:18

If you will allow me to piggy back onto this thread. I am at the stage of installing vent lines to the frp tanks that I built into my boat. Is it necessary to have the tanks vented for water quality or just to relieve pressure as one is filling the tank. I have Peggie Hall's book on getting rid of Boat Odors, she does a good job of explaining Aerobic and Anaerobic bacteria in holding tanks. Nothing is covered in regards to fresh water venting. Jack

Sansaboat · 21-03-2010, 17:23

I do domestic chlorination and sterilizations for a living, and maybe I can add some thoughts:

- use of carbon filters is a double-edged sword - they take out organics (pesticides, odor, etc.), but also take out chlorine. Anything downstream of the carbon filter, is then susceptible to growth of bacteria. Personally, I'd rather have the chlorine than the bacteria.

- the 0.5 ppm of chlorine found in most city waters will not harm your aluminum tanks - it's not strong enough to corrode and it's not very stable - within an hour or so, it's dissipated to nothing, but during that hour, it can kill some bacteria.

- peroxide is what I'd use for aluminum tanks (and plastic for that matter), but the "recommended" dosages that have been posted are great rules of thumb, but there are WAY too many factors involved to use those and be guaranteed of a good sterilization. For example, if you have existing slime (bacteria/mud/organics), you'd need more. If your water is warm, you'd need more. If you have plastic tanks, you'd need more, etc.

- the absolute BEST way to do a sterilization (in my opinion) is as follows:

1. clean the tanks as best you can to remove sediment/slime/mud. Peroxide or bleach cannot kill into any significant "depth" of slime.

2. Add enough peroxide to achieve 20 to 50 ppm (1 ppm = 1 mg/l) of peroxide for 4 hours. You'll probably need to add more during this 4 hour period. Make sure the water flows to all fixtures during this sterilization. Run water to each fixture often - maybe every 30 minutes.

(you are going to need a test kit to verify this level of peroxide. The peroxide is going to be used up as it kills things. I use Hach model 2291700 peroxide test kit. This is important - it verifies that you have a lethal dosage of peroxide for the entire 4 hours.)

3. After the procedure, drain the water tanks to remove dead bacteria/organics and refill with fresh water. If the fresh water is chlorinated, then it's fine. If not, add enough peroxide to get to 5-20 ppm again, and leave it. It's good to go. The peroxide will be gone in a few hours.

I'm sure I should have some disclaimer that if you have 100 lbs of ebola virus hiding our in your water tanks, then you can't sue me if you die. Furthermore, this is no guarantee that there are no "bugs" left in the system. Your local state has a lab that can test for all sorts of bacteria for a reasonable cost.

This procedure also assumes that you might be cruising out there in the wild blue yonder and can't afford to have some bacterial infection. In our camper, I just add a calculated amount of bleach and run it to the faucet and let it sit for 2 hours. If I get some weird bug while camping, I'm not more than 3 hours from a hospital!

Sansaboat · 21-03-2010, 17:24

Quote:

Originally Posted by Stevens 47

If you will allow me to piggy back onto this thread. I am at the stage of installing vent lines to the frp tanks that I built into my boat. Is it necessary to have the tanks vented for water quality or just to relieve pressure as one is filling the tank. I have Peggie Hall's book on getting rid of Boat Odors, she does a good job of explaining Aerobic and Anaerobic bacteria in holding tanks. Nothing is covered in regards to fresh water venting. Jack

Venting is for filling - gotta make room for the new water. Venting does not help water quality.