Water tank issue

[BobHaze]

My 2004 35 CB has 2 aluminum water tanks, and starting this summer the filter just before the Jabsco pump keeps getting gummed up with calcite-like crystals. This usually happens after I've been operating in choppy conditions such that the water in the tank is sloshing around, which I assume means there's a deposit of this stuff in the bottom of 1 or both tanks that gets stirred up. I unscrew and rinse out the filter screen, and I blow into the pex tubing that feeds the pump until I can hear bubbling in the water tank indicating, I think, that the line is clear, at which point the system usually, but not always, operates properly. That is until the next time we experience the choppy conditions that are common here in Nantucket Sound.
Has anyone else experienced something like this? I'm going to ask the yard where the boat is for the winter if they can polish the water tanks, like is done with fuel tanks, but I don't know yet if that's something they can do. Thanks in advance for any suggestions/recommendations.

[BobHaze]

I just posted this in the Command Bridge 32-45 forum, but figured it's more of a general maintenance question...
My 2004 35 CB has 2 aluminum water tanks, and starting this summer the filter just before the Jabsco pump keeps getting gummed up with calcite-like crystals. This usually happens after I've been operating in choppy conditions such that the water in the tank is sloshing around, which I assume means there's a deposit of this stuff in the bottom of 1 or both tanks that gets stirred up. I unscrew and rinse out the filter screen, and I blow into the pex tubing that feeds the pump until I can hear bubbling in the water tank indicating, I think, that the line is clear, at which point the system usually, but not always, operates properly. That is until the next time we experience the choppy conditions that are common here in Nantucket Sound.
Has anyone else experienced something like this? I'm going to ask the yard where the boat is for the winter if they can polish the water tanks, like is done with fuel tanks, but I don't know yet if that's something they can do. Thanks in advance for any suggestions/recommendations.

[Pitou]

What you have going on is aluminum oxide developing on the aluminum sheet inside of your tanks. The aluminum oxide dislodges from the aluminum plate and is then drawn into the pumps screen filter and eventually clogging the system at that point. I've been there.
You need to clean the tank walls by pressure washing and scraping. Recirculating / polishing the water will clean what has already dislodged, but it will only be a very short time before being back to square one.
After cleaning the oxide from the walls you can then coat the inside of the tank to help prevent reoccurrence. Doug shares what he did in one of his prior posts.

Once you mitigate the aluminum oxide issue, two things to always do to take care of an aluminum water tank:
1). Use a filter to remove chlorine from city water when filling your tanks
2). Never pour poly glycol into an aluminum tank to then be pumped through the water system to winterize .. disconnect the intake hose to the screened filter then attach a hose which then goes directly into a bucket of your poly glycol RV water system winterizing antifreeze. The following should help get you started.

Here are a couple of prior discussions on this subject:
viewtopic.php?f=7&t=6643&p=39162&hilit= ... ide#p39162
In this thread my aluminum tank looked just like Doug's before pressure washing and scraping it clean.

viewtopic.php?f=7&t=8966&p=55415&hilit= ... ide#p55415

This thread is of another member's issue of clogged aerator screens is his faucets. Pictures are included of my tanks after cutting access ports into them, also showing aluminum oxide buildup:
viewtopic.php?f=5&t=12364&p=82089&hilit ... ide#p82089

[Pitou]

See my response to your duplicate post in the Albin Maintenance Forum:

viewtopic.php?f=7&t=13503

[BobHaze]

Thanks for all the info, Kevin. I picked up the teak & holly flooring over the tanks (which was screwed and glued!) and found I can see the aft end of the forward tank and the forward end of the aft tank, but very little of the tops or sides of either one. So the only way to cut inspection/cleaning ports either side of the baffles would be to cut away much of the solid fiberglass flooring over the tanks, which were obviously installed before the floor pan was, and in fact the aft tank goes under the door frame between the main salon and forward cabin, as well as under the ice maker. So after briefly considering that or replacing the tanks with plastic or stainless I nixed those ideas as way too expensive and too much demolition/construction.
So I think what I'm going to try this year is to flush both tanks as much as possible in the spring to remove as much of the existing loose aluminum oxide crystals as possible, and use a filter to remove chlorine and calcium from the dock water when filling the tanks such as https://yachtmate.com/product/dock-mate ... -softener/ or something similar, and installing an additional, larger filter between the tanks and the water pump to intercept any remaining crystals in the tanks. The thought is that by removing the chlorine and calcium from the incoming water it should slow or stop the buildup of new crystals on the lining of the tanks; not as well as power washing and applying a sealant, but if this works it will be a hell of a lot cheaper than taking a chainsaw to the interior of the boat, doing all the work inside the tanks then rebuilding the interior.
Interestingly, my friend with a 2004 Nordic Tug 37 (same year as my boat) also has an aluminum water tank but hasn't seen any crystals fluffing off in his tank. I wonder if Albin used an inferior grade of aluminum or something. Who knows...
Anyway, I'll post again next season with a progress report...or lack thereof.

[Nancy]

Hi Bob --

Just wondering how things went with your tanks in the summer of 2022.

We have no evidence of aluminum oxide at this point - knock on wood - but we like to think ahead in case we run into a problem.

As for access holes should you need them, you can access the aft portion of the aft tank by removing the drawer unit below the forward dinette seat (across from the refrigerators). I agree that removing and replacing the tanks would be a horrible job.

I'm 99% certain that the tanks on our boat were fabricated by Luther's Welding, and KevinS tells me that they were very helpful when he worked on the tank on his 31TE, going so far as to provide him with an annotated drawing of the tank showing openings, baffles, etc.

[REBMystic]

Hi Bob --

Just wondering how things went with your tanks in the summer of 2022.

We have no evidence of aluminum oxide at this point - knock on wood - but we like to think ahead in case we run into a problem.

As for access holes should you need them, you can access the aft portion of the aft tank by removing the drawer unit below the forward dinette seat (across from the refrigerators). I agree that removing and replacing the tanks would be a horrible job.

I'm 99% certain that the tanks on our boat were fabricated by Luther's Welding, and KevinS tells me that they were very helpful when he worked on the tank on his 31TE, going so far as to provide him with an annotated drawing of the tank showing openings, baffles, etc.

WRT to the water tank on 31TE. Mine does not have access opening. Has anyone added one? I have wonderful access to the top of the tank. My boat was not used much last year and I believe stagnant water is now sticking up my boat. (I might have sanitary hose replacement project too). I will be doing a lot of flushing in the spring and see if I can get it cleaned out.

Thx
Rob

[Nancy]

Hi Rob -- click on the links up above in this thread for good discussions about 31TE water tanks.

Your boat is in CT, right? And it's been winterized? The fresh water tank should be empty - no stagnant water this time of year. Stinky boats are usually dirty bilges and/or sanitation hoses needing replacement.

[REBMystic]

Hi Rob -- click on the links up above in this thread for good discussions about 31TE water tanks.

Your boat is in CT, right? And it's been winterized? The fresh water tank should be empty - no stagnant water this time of year. Stinky boats are usually dirty bilges and/or sanitation hoses needing replacement.

Hi Nancy,

Yes, in CT. I purchased the boat after winterization, so not sure how empty it is. Pink stuff is in the lines.

I have everything out of the boat, bilges dry. More smell in cabin than head. But I do expect I'll need to replace the sanitation hoses. About 2 more months and I can do some flushing!!

Rob