A Sunday mystery for you (Cleaning/Sealing AL water tanks)

[DougSea]

Hey all,

Have you ever been sitting on the boat on a beautiful Sunday afternoon, saying to yourself "Self, what do those tortured souls who can't use their boats on a beautiful Sunday afternoon do with all that sad spare time?"

I'm here to tell you. We put together strange contraptions. Like this:

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Anyone want to guess? WHAT it is should be easy. The harder question is WHY.

It IS boating related.

[N4QC]

Suspect that it is an air nozzle with a flexible and fixed shaft to shoot at tight and roundabout locations. Cleaning… Or in my case to stir up the bottom of the fuel tank so that my fuel polisher works more efficiently…

Have fun,

[amber jj]

It is a flexable pressure washer wand with a inverter to get in tight places and the backside of things like holding tank hoses to get the mildew off both sides,or under the engines.It is a great idea but don't let it get away from you. You could end up with a black eye.

[Serenity]

My gastroenterologist has one to remove debris and other foreign objects from those hard to reach areas on the vessel.

[DougSea]

Amber JJ nails it. Except for the tank it's being used on. That would be my two 76 gallon aluminum water tanks, aka "The Science Experiment". I've had problems with my water system getting blocked by small granules of aluminum-oxide or some such, so I wanted to take a look inside one of the tanks. With the engine out I was able to easily cut a 4-1/2" hole near the top of the tank. Took a look...gross!

So now I have two holes in each tank, one on either side of the baffle and am in the process of cleaning them prior to a treatment with "Microseal" that will hopefully help ensure that the pitting (most likely from chlorine) is over. I'm also looking at a food grade viralcide to keep the tanks from ever becoming a breeding ground again.

As for the device; yes, it's a pressure washer trigger with a special (read expensive) flex attachment that doesn't lose it's position under pressure. The hook like extension is a gutter cleaner and is in fact for cleaning the front wall of the tanks that I can't otherwise reach. Since I'm personally aware of the power of a pressure washer, having sliced my hand open with one, I AM exercising a good deal of care! More news to come as this project moves along.

[RobS]

Look anything like the water heater I replaced on T-R last week? The tank is aluminum although the outer jacket is stainless.

[DougSea]

Here's a quick view of the interior of the port side tank:

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Yummy!

Black goo and aluminum pitting. What more could you want?

[Halcyon]

Doug, now you have me afraid of what lerks in my tank. I have heard food grade hydrogen peroxide will sanatize and not attack aluminum.
I'm not sure how you plan on sealing your access holes but I had great luck with the products from Seabuilt. www.seabuilt.com
How much to clean my tanks!

[RobS]

Did you consider just replacing them with poly tanks? You could scrap them and get part of your money back. I got a big $4.00 for the AL 6 gallon water heater tank so for the 76 gallon tanks you should get $50 per tank . Once the engine is in and the galley is back together do you no longer have access to the tanks?

[verynice II]

I had the whitish chips analyzed and it was aluminum corrosion. Please keep me posted on your remedy. How many years did you have the chips in the water line?

[DougSea]

I pressure washed the tanks with my contraption. Did three passes (3,000 psi machine) to make sure I got everything. On the last pass I had the shop vac in one port and the gun in the other to capture the piles of aluminum chloride or oxide or whatever the stuff is. Really got the vast majority of the crud out of the tank.

I then dried the tanks by setting a hair dryer on low and leaving it suspended in each tank for about an hour. Followed that with another pass of the shopvac to get the remnants.

After that I did a quick wipe down of the front wall of the tank (where I'd been unable to visually inspect and also the area where I was unable to bring the full power of the pressure washer to bear) with acetone to make sure it was clean.

After everything was clean and dry I used a bleach rated garden sprayer to spray "Microseal" on all of the surfaces of the tanks (link below). This acetone based sealant actually penetrates the surface of the tank, bonds to it, and seals the surface. It is "food grade" approved so no worries about using it in the tank. I was not concerned with over-spray, rather I wanted to make sure every surface got at least one good pass with the spray. Since the spray tube was flexible I was able to bend it around to get all of the surfaces. Once I had sprayed heavily I used a long handled brush to sweep the excess from the bottom of the tank to the "ports" on the bottom where I had previously removed all of the hoses and manifold parts. I had a cup under the openings to catch the excess liquid so that it wouldn't drip into the bilge. Interestingly, there wasn't any. This stuff is very volatile and dries very quickly. Then I stepped out into the fresh air and waited for it to dry. More updates and pictures soon!

SAFETY NOTICE! - Acetone is NASTY stuff. Especially in confined spaces. It's toxic and very flammable. Prior to my spraying I shut off all power and battery switches, opened all windows and ports, and wore heavy rubber gloves and eye protection. While spraying the heaviest fumes were confined to the interior of the tank but they were very noticeable. I paid close attention to how I was feeling and was prepared to get out into the fresh air ASAP if anything seemed amiss. Please be CAREFUL if you follow my path!
How nasty you ask? That chlorine/caustic rated sprayer? It lasted 20 minutes. Then the nozzle fused shut and the hose burst!

Microseal - http://www.microleak.com/

[DougSea]

How much to clean my tanks!

How did I miss this line? I could have self funded the effort!

It really wasn't too bad once you screw up the courage to take a big hole say to your tank!

(Which, by the way, can be interesting! I snapped off 3 guide bits in my hole saw arbor and sliced open my knee before this task was done.)

[DougSea]

Hi all,

So far, so good. It's been a few weeks since I recommissioned my water tanks and I've had no issues. Well, just one - the level sender isn't working since I forgot to reach in and make sure it wasn't glued in the empty position by the Microseal. I'll fix that over the winter.

After treating the tank as documented above I put about 20 gallons of water into the tanks, along with a big dose (20+ ounces) of "Diamond disinfectant 1000" that a friend in the Ice Cream business recommended. It's a food grade disinfectant, sanitizer, virucide that is used on metal tanks and does NOT require a rinse before the tanks are put back in service. I let it sit in the tank while I ran across a few wakes and ran it through all of my fixtures, letting it sit in the lines for an hour.

Then I ran the water until the pump started pulling air and then filled the tanks about half full. The residual disinfectant made the water a bit foamy for a while, but there was no readily discernible taste or odor.

Had I not had the corrosion issues (and the science experiment growth) I think the iodine based disinfectant would have sufficed without the tank sealing. But that wasn't an option for me.

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My plans for the winter layup are to drain the tanks and remove the access ports to let them dry out, and I've made a winterizing adapter to allow me to fill the rest of the system with the normal RV antifreeze. In the spring I'll hit the tanks and lines with another shot of disinfectant, and will use a much smaller dose at each fill up to keep things clean.

If anyone has any questions, please fire away.

[Nordic Spirit]

Take out the tanks and replace them with plastic water tanks, problem solved!

[DougSea]

Take out the tanks and replace them with plastic water tanks, problem solved!

That would have cost over $1,000. And involved even MORE disassembly of the boat. So not really an option I wanted to explore.