Does anybody know what these are from my fresh water tank?

[Bud]

I heard back from TRAC Ecological, Patrick LeClerc. He said the sample deposits I dropped off easily disolved in 2.5 % ratio of PSR. I also asked him if this product was safe to use on aluminum tanks and if so should I flush the tank after with anything to nuetralize any acid in the product. He said, "At that low concentration PSR is safe for the tanks yes, and to make the rinsing process go faster, neutralizing the tank with baking soda will help for sure."

Bud

 

[OldDan1943]

Bud, do you have water tanks drains or must you pump them until empty?

 

[Bud]

I have to pump them to drain
Bud

 

[OldDan1943]

I have to pump them to drain
Bud

Check your water tanks and see if there is a plug you can remove to install a drain.
My AT34 has a 'plastic' water tank. It had a 3/4 plug at the base. I removed it and installed a outside spigot with a length of how to reach a point near the bilge pump. Works great for draining the tank and washing out the bilge

 

[JP2]

So, which is best??? To drain the aluminum tanks Empty for long winter periods of low ops/use? Or, keep the tanks at the FULL peg at all times?? (Freezing is not a factor and the local city water is likely chlorinated to some degree.)

 

[OldDan1943]

Check your water tanks and see if there is a plug you can remove to install a drain.
My AT34 has a 'plastic' water tank. It had a 3/4 plug at the base. I removed it and installed a outside spigot with a length of how to reach a point near the bilge pump. Works great for draining the tank and washing out the bilge

LOL I suffered a brain fart. I have a metal/Al water tank. I wished they were "plastic".

 

[Pcpete]

I am addressing the same situation on my Bayliner 3818. Unfortunately there are no inspection plates, yet. The tank is small by comparison, 80 gallons, but about five feet long with two baffles, and under a passageway. My plan is to install three reasonablely large oval holes once I have the tank exposed. Next I’ll scrape, wire brush, flush, steam clean then a white vinegar wash down. I’ll fabricate cover plates using the section cutout “waste” bonded to a larger piece of one eighth aluminum and prefit each to the tank. I’ve ordered a food grade tank called “Brewcoat” from Sound Specialty Coatings Coating for small and large water tanks, boat water tanks,sistern coating, safe for food contact, aquaculture, fish safe. For use on potable water tanks,brewing tanks, etc. located near Seattle. I asked a guy in our Yacht Club who does all sorts of tank maintenance some very pointed questions about the right product for the job and he suggested Brewcoat, a food grade industrial tank coating. I called the company and found them to be very knowledgeable, friendly and flexible. I went over the prep plan with “Nancy” and she agreed with my preparation plan. At a minimum, two coats are required and I plan to roll it on. When we talked about installing the tank cover plates, she said I could use the Brewcoat as a sealer, but I’d never get them off again. I’m thinking more toward a food grade caulk but may seal with the Brewcoat.
I did smile at some of the gallows humor, but fully understand the frustration with situations like this. I know the Admiral isn’t going to be happy that I have to do another fairly large project this year and any of my attempts at humor will be ill received.
Dan, I hope this option could work in your case too
Pete

 

[Steve DAntonio]

Sea-Built makes aluminum inspection port kits.

Please do not use a wire brush to clean an aluminum tank, the wire, steel or stainless steel, is more noble than the aluminum; the brushing will leave behind some metal residue, which will be cathodic to the aluminum, thereby causing the aluminum to corrode. Only non-metallic abrasives should be used on aluminum.

I don't wish to burst your tank coating bubble, but I can assure you, it is virtually impossible to successfully coat the inside of even a new aluminum tank, much less one that's been in service for years (has the tank specialist at your yacht club or Nancy at Brewcoat ever done this?), there is absolutely no way you could ever get it clean enough to achieve reliable adhesion. Furthermore, where ever there is a breach in the coating, and there will be, even it just at the fittings and access port edges, water will migrate beneath the coating, where the perfect environment for poultice corrosion will exist. Coating, therefore, can actually accelerate corrosion. For more on aluminum corrosion mechanisms see https://stevedmarineconsulting.com/understanding-and-preventing-aluminum-corrosion/ This article covers aluminum and coating-induced corrosion https://stevedmarineconsulting.com/paint-and-aluminum-how-to-ensure-a-good-mix-2/

Over the years I have encountered many who have tried to coat the inside of aluminum fuel and water tanks, I have yet to encounter one long-term success story. If anyone has done this successfully, please do share the details.

 

[Irish Rambler]

Stainless is painless, fit it and forget it.

 

[Pcpete]

Steve, thanks for your input. I’m well aware of the metal brush issue, actually I was speaking more as a cleaning metaphor. I’m also aware of the difficulty getting and keeping a long term bond. I may do an alodine precoat as a primer. I’m expecting the tank to develop penetrations from the outside are as much as a risk as anything. My goal in going this route is to get a few years out of it. I want to add a tank under the master berth but that in itself is going to take more planning and construction than I have time for this year. I like to have 90% of my materials on site before I start a replacement project, so delaying the inevitable allows me to get an accurate measurement of the available space so I can optimize the replacements. The aluminum tank has to come out with a sawzall and replacement involves two smaller tanks. That is, unless I remove all of the fastenings to the head and bathtub, and that’s mot going to happen.
This year has been one of other major projects put in a crunch by cervical surgery. Such is life.
Thanks for your concern.

 

[Steve DAntonio]

It's a lot of work for e temporary fix, but I understand. The failure mode often involves sections of the coating flaking off and clogging pick ups, strainers, pumps and filters.

Two smaller tanks, preferably polyethylene, when you are able to do it, makes good sense.

To my immense frustration, some builders continue to use aluminum for potable water tanks.

 

[firehoser75]

Steve,
As many boats have aluminum water tanks in them, what is the best way to store them over the winter (in active) season. Leave them full (assuming freezing is not an issue in the area) with relatively soft municipal water, or empty them and let them "dry out"?
Thanks,
Tom

 

[Steve DAntonio]

The enemy of aluminum is stagnant, oxygen-depleted water, i.e. that which you are likely to find in the tanks of a vessel at rest; it establishes the ideal environment for poultice corrosion. In light of that, I'd leave the tanks as empty and dry as possible.

 

[firehoser75]

Thanks Steve, that clears it up.

 

[psneeld]

Passed along for info...


http://tinyurl.com/y6ru7mg5

"... characteristics to determine their singular effect on corrosion of aluminum.
These characteristics included copper ion, dissolved oxygen, and hardness.
In general, they determined that in the absence of copper ions, dissolved
oxygen, and hardness nodular type pitting is prevented. They concluded that
the characteristics which are necessary for the initiation of pitting include
temporary hardness, chlorides, copper, and dissolved oxygen. It was also
found that the water composition is more influenced on the cnrrosion of
aluminum than is the composition of the aluminum specimen (79).
Porter and Hadden also investigated the effects of these parameters on
the maintenance of pits. These tests were preformed by transferring specimens
to other controlled aqueous environments after pitting was initiated.
It was found that dissolved oxygen was essential for maintenance of pitting
as pitting ceased in de-aerated waters. The removal or absence of copper
ion, however, did not prevent the maintenance of pitting, but the rate of
pitting was slowed."

(Further notes on the link from my engineering friend)


"Note the statement "pitting ceased in de-aerated waters"

What it boils down to is if you store mineral rich water, hard water, that may have a high choride content and be in contact with copper alloys you may have corrosion in your aluminum tank. There is a type of pitting corrosion called an "oxygen depletion cell" that occurs under a layer of crud that permits oxygen rich water to react with oxygen depleted water to create an localized alkaline environment which dissolves aluminum.

There is no single sentence explanation, treatment, cure or advice for this stuff…….."

 

[Bud]

Just follow up. I did use the treatment from trac ecological called PSR at 2.5% for 30 hours. Here are the before and after pics.

 

[Bud]

More pics

 

[Bud]

I did use baking soda and water to rinse tank and neutralize any residual treatment solution.
Bud

 

[kchace]

Wow what a difference. That looks great.

 

[ben2go]

Bud, looks like you got an excellent outcome. Good work.

 

[Steve DAntonio]

That is impressive, once again TracE is a very good resource.

 

[psneeld]

Here's some info on tank coatings for those that may want to try it...


AEROSPACE COATINGS FOR COMMERCIAL, GENERAL AVIATION, MILITARY AIRCRAFT BY PPG - PPG Industries - Aerospace



Meets those aerospace manufacturer requirements.

 

[jungpeter]

Hi Bud,

An interesting result! But at something approaching $90/gallon delivered for PSR, even at only a 2.5% solution, that's about $400 to flush my water system. Ouch! And Trac recommends double that for "moderate" scale...

I guess it's my my money, and my choice. Sure wish I had a 316L tank instead of aluminum.

Sigh.

Pete

 

[Pcpete]

We have completed installing the “Brewcoat” epoxy to the inside of our aluminum tank. I’ve flushed the tank a couple of times and am satisfied with the results. The water tastes like, well, water. The epoxy was reasonably easy to work with, but, like all coatings, messy. Time will tell if it looses its bond anywhere but if trying to remove it from an area with no preparation is an indication, it’s not coming off any too soon.

 

[Steve DAntonio]

Good luck with it Pete, keep us posted please.

 

[Bud]

I bought 2, 5 gallon pales of it for $225 each at BOW. I used one for each 250 Gallon tank.
Bud.