How to treat fresh water in Al tanks??

[malbert73]

Hi everyone,
It seems that my water system purification method for the last many years, Aqua Mega, isn’t available anywhere in the US. I ran out.

Because I have aluminum water tanks, I pre-filter the chlorinated marina water into my tanks and add Aqua Mega which is a dichloroisocyanurate formulation which is reportedly safer than chlorine/bleach for aluminum water tanks.

Anyone have a solution for “preventive” water treatment for aluminum tanks?

Thanks!

[rslifkin]

I personally don't filter the chlorine out before filling. As long as I'm starting with clean tanks, the water usually stays good from the tiny bit of chlorine in city water. And my tank still looks pretty good inside after 35 years (a little corrosion, but nothing major), so I don't think that's enough chlorine to be a problem. Adding bleach is definitely not recommended, however.



If you need to shock the system, hydrogen peroxide won't hurt the tank, but it's debatable as far as how useful it is as a water system sanitizer. A little bit in the tank can remove funky smells from the water if that's an issue, however.

[wsmurdoch]

Clorox Zero Splash Bleach Crystals are sodium dichloroisocyanurate.
https://www.clorox.com/products/clor...tals/original/
https://www.thecloroxcompany.com/wp-...ar-Scent_2.pdf

Clorox Pool Tablets are the similar trichloro-s-triazinetrione.
https://www.cloroxpool.com/products/...r-small-pools/
https://kik-sds.thewercs.com/private...d__%7Evalue%7E

...and, even for us with plastic water tanks, our hot water heaters are usually aluminum tanks.

[LittleWing77]

That's a Peggie Hall question.

Reach out to:
peghall
https://www.cruisersforum.com/forums...all-52296.html


For future reference, also make a point of purchasing her book and keeping it onboard - it's a comprehensive guide to troubleshooting and fixing all marine plumbing issues, not just heads, as the title would suggest.

Fair winds!
LittleWing77

[sailing_gal]

NEVER NEVER NEVER put bleach or chlorine into an aluminum tank! It reacts with the Al and will eventually eat it away. You will first notice the problem when you see beige colored crystals congregating in your fresh water filter and in the mesh screens of your faucets. I have an Al tank on my boat and always pass any water from a marina through a carbon filter before putting it on my boat. Even when they claim there is no chlorine in the water. I keep test strips on board to double check it. There are other chemicals you can use to clean the tank if you are concerned- some people use forms of hydrogen peroxide. I just filter all the water and my tank is fine. If you get smelly stuff coming from the faucets, it is generally in the lines, not the water tank. You can clean the lines by soaking in a bleach solution, but bypass the tank.

[altinr]

Aquabon

I filter water from hose with rv filter, and add Aquabon.
I have a sediment and a charcoal filter in my fresh water system.
If water gets funky, refill tanks. But usually the problem is the hoses. Fill a bucket with water and chlorine bleach, 1 cup/gallon. Hook bucket directly to pump, fill hoses for an hour, then flush. No chlorine goes in aluminum tanks.

https://www.gearbuyer.com/products/aquabon-drinking_water_freshener.html

[flyingfin]

Ammonia

[malbert73]

Thanks all for your feedback. Key is to prevent water from turning funky in the lines if it sits for a few weeks, and protect Al tanks.

Anyone know what’s in Aquabon or this?

http://www.starbrite.com/category/wa...ment-freshener

And the Clorox product is intriguing and tough to know how much to use.

Thanks on the Peg Hall reference- have the book but out on loan currently so will grab

[BillKny]

Originally Posted by malbert73

Hi everyone,
ause I have aluminum water tanks, I pre-filter the chlorinated marina water into my tanks and add Aqua Mega which is a dichloroisocyanurate formulation which is reportedly safer than chlorine/bleach for aluminum water tanks.

It might have been "reported safer" but like many things "reported" it is absolutely NOT true.

Dichloroisocyanurate, either as the free acid or sodium salt or hydrate, is simply a way of chemically packaging free chlorine in an easy to handle solid. When added to water it slow decomposes, and generates hypochlorous acid. Which is exactly the same thing you get when you add sodium hypochlorite solution ("liquid chlorine bleach") to water, or when you dissolve chlorine gas in water. Hypochlorous acid is the actual oxidative chemical that does the killing.

It has no significant advantages in corrosion reduction over any other form of maintaining a low level of "chlorine" for biocontrol, no matter what the guy selling it might tell you.

[rslifkin]

Originally Posted by BillKny

It might have been "reported safer" but like many things "reported" it is absolutely NOT true.

Dichloroisocyanurate, either as the free acid or sodium salt or hydrate, is simply a way of chemically packaging free chlorine in an easy to handle solid. When added to water it slow decomposes, and generates hypochlorous acid. Which is exactly the same thing you get when you add sodium hypochlorite solution ("liquid chlorine bleach") to water, or when you dissolve chlorine gas in water. Hypochlorous acid is the actual oxidative chemical that does the killing.

It has no significant advantages in corrosion reduction over any other form of maintaining a low level of "chlorine" for biocontrol, no matter what the guy selling it might tell you.

I remember Practical Sailor doing some testing on this and finding it did show less corrosion on their aluminum samples. They didn't dig into why it would show less corrosion, but for whatever reason, it did.

[Bill O]

Originally Posted by BillKny

It might have been "reported safer" but like many things "reported" it is absolutely NOT true.

Dichloroisocyanurate, either as the free acid or sodium salt or hydrate, is simply a way of chemically packaging free chlorine in an easy to handle solid. When added to water it slow decomposes, and generates hypochlorous acid. Which is exactly the same thing you get when you add sodium hypochlorite solution ("liquid chlorine bleach") to water, or when you dissolve chlorine gas in water. Hypochlorous acid is the actual oxidative chemical that does the killing.

It has no significant advantages in corrosion reduction over any other form of maintaining a low level of "chlorine" for biocontrol, no matter what the guy selling it might tell you.

+1

[malbert73]

Originally Posted by rslifkin

I remember Practical Sailor doing some testing on this and finding it did show less corrosion on their aluminum samples. They didn't dig into why it would show less corrosion, but for whatever reason, it did.

Yes that’s what I read and have based last 5 years on...

[wsmurdoch]

From Practical Sailor July 2015:

"Dichlorisocyanurinate: Common in swimming pool tablets, chlorine in this form has several advantages. Chlorine levels are stabilized by a chemical equilibrium, resulting in a more stable and more durable treatment, and reducing the amount required. Additionally, the released chlorine generates cyanuric acid, an effective corrosion inhibitor for aluminum, reducing aluminum corrosion by 10 to 40 times compared to bleach treatment. Both the U.S. Environmental Protection Agency (EPA) and World Health Organization (WHO) approve this method."

...and then:

"We were concerned about pitting in aluminum tanks. The highest concentrations were in the tank cleaning and sanitation products. Since these are only used once a year for no more than 90 minutes while the tank is being cleaned and flushed, we limited the test coupon exposure to only 48 hours. None of the products caused significan’t pitting, but Puriclean (dichlorisocyanurinate) was clearly less corrosive to aluminum than other sanitizing treatments. When we tested freshening treatments and tap water, we found the same trend; AquaMega Tabs (also based on dichlorisocyanurinate) were far less damaging than other treatments, and less damaging than tap water alone.

While most disinfecting products are based around 2 to 3 ppm of free chlorine, 0.5 ppm residual chlorine is enough for safe water, and owners of aluminum tanks should buy test tapes and use only the minimum amount of disinfectant required."

There are photos of the corrosion coupons.