Full or empty water tank in tropical temperatures

[Siberian Sea]

Some folks here have suggested the use of bleach in your water tanks to reduce the growth of bugs. I would caution against this if your tanks are aluminum or like mine stainless steel as this agent shall attack the metal tanks. Bleach is corrosive on many things.

[a64pilot]

I have looked a lot to try to determine the dosage rate for Hydrogen Peroxide.

I can’t find an official source that uses it for water disinfection, I can find many sources on how it’s used to treat water for iron content, but not disinfection.

If anyone has a link, I’d appreciate it.

[letsgetsailing3]

This is a great topic.

After reading through all the postings, I'm still not at all sure of the best answer.

[hellosailor]

You can blow lines dry with a shopvac exhaust hose, just hook it up and let it run.

Fuel tanks full, yes--but with a good dose of diesel stabilant, because "pump fuel" really is meant to be used in 90 does and the stabilant extends that. Also, with all vents sealed to keep air and moisture out. PS did some tests on tank vent gizmos that trap moisture, they found that vents do manage to pass in enough moisture to leave water in your tank, never a good thing.

[Scotty Kiwi]

Originally Posted by S/V Illusion

Off topic regarding the latter issue but lots of disagreement regarding fuel tank full of old diesel. Diesel doesn’t age well

Diesel with Diesel Conditioner

[Scotty Kiwi]

Originally Posted by letsgetsailing3

This is a great topic.

After reading through all the postings, I'm still not at all sure of the best answer.

Does that mean their is not a best answer, and it does not really matter (up to a limit of making sure water is clean)?

[Singularity]

Originally Posted by a64pilot

I have looked a lot to try to determine the dosage rate for Hydrogen Peroxide.

I can’t find an official source that uses it for water disinfection, I can find many sources on how it’s used to treat water for iron content, but not disinfection.

If anyone has a link, I’d appreciate it.

Very good point. I frankly am suspect of most peoples' application of hydrogen peroxide to clean large tanks unless they somehow have access to industrial strength (30+%) stuff, or use it with near empty tanks. Pubmed.gov is the google for much science stuff. Generally a 1-3% solution and time should fry the bugs, but I can't cite a reference (most studies and clinical practice seem to use these concentrations, maybe as high as 10%, but that's pretty harsh). This said, dumping a little bottle of 3% hydrogen peroxide that you buy at the store isn't going to do a whole lot once diluted in a huge tank except clean the filler tube on the way down. That people have success with this practice tells me that they didn't have an contamination problem in the first place.

If hydrogen peroxide in solution is the goal, arguably the easiest/cheapest method to get high concentrations is to use sodium percarbonate powder (aka Oxiclean, aka sodium carbonate peroxyhydrate). When added to water it breaks down into hydrogen peroxide, sodium, and carbonate. If the tank/plumbing material can tolerate hydrogen peroxide, you can really nuke the tank/plumbing system with just a little Oxiclean, which is easy to keep a lifetime supply on board for a few buks (just make sure the content is exclusively sodium percarbonate [+/- sodium carbonate] without artificial scents or other stuff added). No chlorinated anything involved. I'm a huge fan of the stuff. It does leave a little white residue (sodium carbonate ash) when used, but this is inert and can be safely consumed in reasonable amounts as would be used in tank sanitizing (sodium carbonate is used as a food additive).

See also:
https://www.ams.usda.gov/sites/defau...0TR%202014.pdf
"Historic Use:
Sodium carbonate peroxyhydrate has been used in organic production as an algaecide, sanitizer and disinfectant since its addition to the National List in 2010. There are no food uses for this product.
Organic Foods Production Act, USDA Final Rule:
Sodium carbonate peroxyhydrate is currently on the National List as:§ 205.601 Synthetic substances allowed for use in organic crop production.
(a) As algaecide, disinfectants, and sanitizer, including irrigation system cleaning systems, (8) Sodium carbonate peroxyhydrate (CAS #-15630-89-4)—Federal law restricts the use of this substance in food crop production to approved food uses identified on the product label."

[Exile]

Originally Posted by hellosailor

You can blow lines dry with a shopvac exhaust hose, just hook it up and let it run.

Fuel tanks full, yes--but with a good dose of diesel stabilant, because "pump fuel" really is meant to be used in 90 does and the stabilant extends that. Also, with all vents sealed to keep air and moisture out. PS did some tests on tank vent gizmos that trap moisture, they found that vents do manage to pass in enough moisture to leave water in your tank, never a good thing.

As others have pointed out, it's not certain if even letting a Shopvac run would eliminate all moisture in fill & vent lines, especially in humid environments.

Off topic, but I'm not sure if sealing off vent lines for diesel fuel tanks is prudent, especially if the tanks are left full as you suggest. Diesel is certainly a lot more stable than gasoline, but still . . . .

MaineSail did some testing awhile back of actual diesel tanks he left over the winter in an unheated environment in Maine. His observations were that condensation from vent lines wasn't significant enough to cause the amount of water intrusion that results in fungus growth and its resulting problems. As I recall, he surmised water was more likely getting in via deck fills due to deteriorated o-rings. Fwiw . . . plenty of other threads on this particular topic.

[Exile]

Originally Posted by letsgetsailing3

This is a great topic.

After reading through all the postings, I'm still not at all sure of the best answer.

Me neither. I've always used small amounts of bleach but had frankly forgotten that it can be corrosive on stainless steel tanks (which I have). I wonder how much of a problem this really is given the small quantities involved, along with flushing the tank shortly after adding the bleach?

[a64pilot]

Originally Posted by Exile

MaineSail did some testing awhile back of actual diesel tanks he left over the winter in an unheated environment in Maine. His observations were that condensation from vent lines wasn't significant enough to cause the amount of water intrusion that results in fungus growth and its resulting problems. As I recall, he surmised water was more likely getting in via deck fills due to deteriorated o-rings. Fwiw . . . plenty of other threads on this particular topic.

While I am a huge fan of his and sometimes disagree with his results, I can almost never find any fault with his testing methodology.
His test was I believe to determine whether or not a fuel tank will cause condensation to form inside of the tank over time, his test was negative, over a very long time, he didn’t see any condensation at all, not even a drop I don’t believe.

However the issue in our boats isn’t whether or not a tank will condensate, the actual issue is will fuel if exposed to moisture laden air, absorb water?
The answer is yes, that fuel is hydroscopic if I use the term correctly , that is if there is moisture laden air above the fuel, the fuel will absorb some of the moisture, the tank breathes due to temp changes and brings in more moisture laden air tomorrow and the fuel absorbs it.
A drop in temp of the fuel will lower the amount of water it can hold in suspension and water may drop out of suspension, and voila, you now have liquid water in the bottom of your tank.

There are of course desiccant filters that can be put onto fuel vent lines that will absorb the moisture before it gets to the fuel, they have to be monitored of course and changed out whenever needed, many are clear tubes with granules that change color from blue to pink to indicate when they need to be changed, some of the filter cartridges can be dried out in an oven, sealed in a zip loc bag and re-used.

So bottom line, his test in my opinion was done correctly and did in fact in my opinion prove that an empty tank will not fill over time with water from condensation.

However that isn’t the issue, the issue is will fuel over time if exposed to moisture laden air absorb water, and the answer is yes it will.

In the Military before we could fill a helicopter with fuel from any source, tank farm, truck etc. we had to do an Aqua Glow test to determine how much water was dissolved in the fuel, and if it was above a certain level, we had to recirculate the fuel through a filter / drier to remove the moisture, Polish the fuel if you will.
I was told, but do not know for sure that the part of the filter that removed the water from the fuel was the same thing in Baby diapers that absorbs pee and turns to gel, but with the proper filter, fuel can be dried.
Now this filter was about two feet tall and at least one foot around too, so I doubt it could be used in boats, but there are filters that will absorb water from fuel that is dissolved into the fuel, and I believe they clog when they absorb much water.
I don’t know how effective they are.

Now thankfully Diesel isn’t real hydroscopic, just a little or we would have real problems.

[sailorboy1]

Originally Posted by a64pilot

I have looked a lot to try to determine the dosage rate for Hydrogen Peroxide.

I can’t find an official source that uses it for water disinfection, I can find many sources on how it’s used to treat water for iron content, but not disinfection.

If anyone has a link, I’d appreciate it.

I'm not going to look for the link, but its:

5 gal of 30% hydrogen peroxide per 1000 gals system to treat

unless you can get industrial strength peroxide it isn't practical

[sailorboy1]

Originally Posted by CSY Man

Somebody mentioned vinegar is better than chlorine for storage: Experts Agree?

I disagree. The only reason vinegar would work is to lower the pH level of the water to point that it kills the bacteria. So you know what that pH is? You don't plus vinegar is a weak acid and it going to take a lot.

Bleach (sodium hydrochlorite) is the World Gold Standard of drinking water disinfection. Yes at high doses it will corrode. In fact it will corrode ANYTHING even plastic given time. But at small maintenance dose it is pretty safe (bet there are steel water pipes around town that have had water with bleach running in them for 50+ years).

If you are concerned about your metal tanks only add a small amount for a storage dose of say 1/2 tablespoon per 50 gal and leave full. When you get back drain half and add 2 tablespoons and refill the tank. Allow to sit 1 hours and flush through the lines. The refill the tank and flush it again.

People like to make everything soooooo hard.

BTW - water has things like calcium etc in it that are going to also react with the bleach pH and tend to scale. This very thin scale layer acts as a protective corrosive layer. There's more to total water treatment than just bleach etc.

[S/V Illusion]

Originally Posted by sailorboy1

I'm not going to look for the link, but its:

5 gal of 30% hydrogen peroxide per 1000 gals system to treat

unless you can get industrial strength peroxide it isn't practical

Sounds right. Every city which has some industry will also have chemical formulator businesses which can supply concentrated peroxide solutions. More expensive than hypochlorite but safer, longer effective disinfection period and more effective and without the inherent bad taste, safety and hazard issues.

[a64pilot]

Originally Posted by sailorboy1

I'm not going to look for the link, but its:



5 gal of 30% hydrogen peroxide per 1000 gals system to treat



unless you can get industrial strength peroxide it isn't practical

12% is about as strong as is easily sourced, directions say to use three times as much as 35% of course.

So, .5 gl of 30% per 100 gls, is 1.5 gls of 12% per 100 gls.
Cost is about $35 per gallon, for my 150 gl tank it would take 2 gls of 12% or $70 of hydrogen peroxide.

Hydrogen peroxide is of course rocket fuel among other things and is extremely reactive at higher concentrations. Assumption is 30% is safe of course, but will likely pretty quickly degrade so it’s not something to store for a long time before use.

$70 of hydrogen peroxide vs literally a few cents of bleach is a no brainer unless your hyper concerned about corrosion.
I am, but $70, plus difficult to source, plus short shelf life is tough to overcome.

[sailorboy1]

It is rocket fuel. I worked for a company that used a lot of it to clean cooling towers. A few years ago Homeland security decided the 35% was too dangerous to be around and we were then using something like 25%. Well that is a lot more 5 gal pails to carry up the stairs to treat a 20,000 gal system and at 50 lbs each was a LOT of work and wear and tear on us.

Then we discovered we could realabel the 35% as 32% and it would fall into the blending tolerance. so we just relabeled the 35 to 32.




% may be off some, I suffer from CRAFT and it's been a few years now