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

I just installed a inspection plate in my fresh water tank and In the process of cleaning it out I was finding these deposits. They break apart easy. Maybe calcium? I also am wondering what to clean it with.

Bud

I don't know, but the picture makes me want to not look inside my tanks!

Calsium and magnesium carbonate, it’s in most water systems usually seen as small particles in your faucet aeriators.

Tank oysters. What kind of antifouling paint do you use in your tank?

Do you think lime will dissolve them?
Bud

If the lime doesn't get them....surely the gin or tonic will !!

Benthic2 said:

If the lime doesn't get them....surely the gin or tonic will !!

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now that's funny right there.

Pretty sure these are aliens eggs, I would not look in the tank not to risk one of these jump and stick to your face, you have been warned!

L

If you really want to look inside your tanks, do it with a flashlight and mirror. That way the alien eggs will attach to the mirror, not your cheeks.

If your tanks are aluminum and there is chlorine in the water you may be seeing aluminum chloride.

Yes my tanks are aluminum

Hi Bud,

Rather than a facetious, flippant answer to your posted question, which does little than waste bandwidth, I would suggest an honest response.

I agree with others, that what you have discovered is probably aluminum chloride, a precipitate that forms from the reaction of hypochlorite (a generic name for bleach, or chlorine) that is commonly found in city water systems and the aluminum alloying elements found in marine aluminum alloys. Over time, the aluminum chloride (which is harmless in of itself) forms in your water tank, and most of the time, is invisible in your fresh water system. In some cases, if your water appears cloudy, and your sink fixture strainers become clogged, the chloride becomes visible. It looks like snow in the water, and if the water is allowed to evaporate, feels like a soft gypsum-like powder residue.

In your case, as you state the deposits "...break apart easily.", that's a good clue. Other than that clue, and the white color, you're only recourse to knowing definitely the answer to your question is to submit your sample to a testing facility to perform a spectrographic analysis. I'd love to hear the outcome of such an analysis.

Unfortunately, the downside to the development of an aluminum chloride precipitate in your water tank is the likelihood of development of other, related precipitates that are NOT soft and easily removed. These tend to form "crusticles" (for want of a better term) on the interior of aluminum tanks, leading to corrosion pockets under them, eventually failing the tank.

I'm attaching a picture of such a crusticle, and wonder if you've seen any such attachment to the interior of your tank? In my opinion, the aluminum chloride is simply an irritant, but difficult to flush from marine water systems, and possibly a harbinger of worse to come. But again, just my opinion...

Regards,

Pete

Now I definitely don't want to look in my tanks

I appreciate the helpful answer.
Here are some more pics

More pics of inside water tank

That’s why I avoid aluminum water heaters. They do the same hing. I’ve also seen a jelly like substance clinging to the walls of aluminum water tanks.

I don’t know why boat builders use aluminum water tanks. A good plastic tank should be cheaper and easier to keep clean.

I'm not sure how basic Aluminum Chloride is, but if you put some of it in a acid, say vinegar, and it fizzes then it's either some sort of carbonate or bicarbonate. The stronger the acid the more the reaction. I can't imagine A C doing that.

Hi Bud,

Thanks for posting some additional pictures of your tank interior. I would suggest that leeman's suggestion regarding an attempt to dissolve the material in distilled white vinegar may provide some clarity, and may well shed light on this issue.

A question for leeman-what do you hypothesize as the source of the carbonate ion, which bonds with water, to potentially form a carbonate residue inside a boat's fresh water tank? Carbonates typically are found in such as terrestrial caves, the result of relatively-acidic water dripping through limestone. I'm open to suggestions!

I've asked many folks for their opinion on "stuff" such as found in Bud's tank, but haven't had confirmation of anything yet. Lots of opinions (like mine!), but little evidence. I've been told such deposits could be aluminum oxide, washed off the surface of the tank as it oxidizes. But oxides of aluminum are REALLY hard (they're used as abrasives), and the deposits I've seen in free-floating form inside water tanks aren't. In addition, aluminum oxide is tenacious stuff-it doesn't want to leave it's aluminum home! Other possibilities for Bud's deposits are possibly some form of a magnesium chloride, as magnesium is the major alloying element in the (typical) 5000-series marine alloys, and the chlorine is floating around in city water inside the tank.

So back to Bud's original question-wha zis? My answer-beat's me, but IMO it's aluminum chloride. Given he's got access to the interior of the tank, a thorough cleaning with good old soap and water may be in order, and perhaps an attempt made to dislodge one of the crusticles seen in the tank seams. And an attempt to crush one of his nodules would be instructive as well.

Regards,

Pete

jungpeter said:

Hi Bud,

Thanks for posting some additional pictures of your tank interior. I would suggest that leeman's suggestion regarding an attempt to dissolve the material in distilled white vinegar may provide some clarity, and may well shed light on this issue.

A question for leeman-what do you hypothesize as the source of the carbonate ion, which bonds with water, to potentially form a carbonate residue inside a boat's fresh water tank? Carbonates typically are found in such as terrestrial caves, the result of relatively-acidic water dripping through limestone. I'm open to suggestions!

I've asked many folks for their opinion on "stuff" such as found in Bud's tank, but haven't had confirmation of anything yet. Lots of opinions (like mine!), but little evidence. I've been told such deposits could be aluminum oxide, washed off the surface of the tank as it oxidizes. But oxides of aluminum are REALLY hard (they're used as abrasives), and the deposits I've seen in free-floating form inside water tanks aren't. In addition, aluminum oxide is tenacious stuff-it doesn't want to leave it's aluminum home! Other possibilities for Bud's deposits are possibly some form of a magnesium chloride, as magnesium is the major alloying element in the (typical) 5000-series marine alloys, and the chlorine is floating around in city water inside the tank.

So back to Bud's original question-wha zis? My answer-beat's me, but IMO it's aluminum chloride. Given he's got access to the interior of the tank, a thorough cleaning with good old soap and water may be in order, and perhaps an attempt made to dislodge one of the crusticles seen in the tank seams. And an attempt to crush one of his nodules would be instructive as well.

Regards,

Pete

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I would think the carbonate is CaCo3 or CaMgCo3. Could also be ?HCo3. Likely from the water. Well water in my neck of the woods is very high. Although the rivers are significantly lower, because they originate in the mountains they still contain low levels of carbonate/bicarbonate. At higher PH's it tends to express as bicarbonate. You may have very pure water in your home port, but where you tie up for the night might be getting their water from a well.
I'm retired so getting a little rusty at this...

Is there any simple test I can do to find out what it is or at least rule something out.
Bud

Bud said:

Is there any simple test I can do to find out what it is or at least rule something out.
Bud

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Lab tests cost money. Maybe start with asking if your marina/municipality has a water test result. If you use their water a lot this could be the source. Have a look at it and check the ph, carbonate/bicarbonate level. They'll also have things like sodium(Na), and calcium(Ca) on there. You can also do the acid test. Regular vinegar is 5% acetic acid, but you can get pickling vinegar at 7% and cleaning vinegar at 10%. Get the strongest you can find and drop some of the deposit in it.
As for the aluminum chloride, I haven't a clue.

I droped a piece in a cup of white distilled vinegar and I got a few small bubbles at first and then nothing and after an hour it is still pretty hard. I tryed dropping a peice in a cup of CLR and after an hour nothing has changed,
Bud

Bud said:

I droped a piece in a cup of white distilled vinegar and I got a few small bubbles at first and then nothing and after an hour it is still pretty hard. I tryed dropping a peice in a cup of CLR and after an hour nothing has changed,
Bud

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I had a feeling this would happen. If nothing changes in a few more hours I think you've eliminated one possibility.

Overnight the piece in the vinegar is still in tact and the same. The piece in the CLR was smaller and crumbled when I picked it up.
Bud

Hi Bud,

Based on your tests with various mild acids (vinegar and CLR), sounds to me like your chunks of "stuff" are something other than aluminum chloride or a carbonate of some sort. My next best guess is a loose piece of one of your "crusticles" forming on the walls of your tank. If you can reach one of those deposits still attached to the walls, can you attempt to dislodge one of them? If they're strongly attached and very hard, methinks your're beginning to form similar crusticles as the one's I displayed. And again, I believe only a spectrographic analysis can reveal what your chunks actually are. You might call around for an estimate on such a test. Might be less than you think.

Presumably, as (if I recall) the water tank in the GB49 is rather inaccessible, and you've gone to the effort of putting in an inspection plate, you have some sort of issue (other than curiosity) regarding your water tank. Judging from your photos, unless the tank's leaking, my take on the tank itself is to clean it as best you can, leave the crusticles in place, and be happy. There is little evidence you have major issues inside. Looks nasty, but doesn't look that bad to me. YMMV here, of course.

If your concern is water quality from such a tank, Ms. Peggy Hall is the authority on how to clean and purify fresh water systems aboard pleasure boats. Get her book, follow her suggestions explicitly, be happy. Beyond that, water quality test facilities are routine in most cities. They can test water samples for both dissolved solids, and biologics. Your tank's drained, so button it up, fill it and let it sit for a few weeks, draw a water sample through one of your fixtures, and take it to a water quality test lab. That'll reveal any issues with your source water, any remaining contaminants in the tank, and/or with the rest of your fresh water supply system in the boat.

If you've got a leak, that's a new ball game, and a topic for another thread.

Regards,

Pete

Our town switched its municipal water source from a river to a well a number of years ago, and the high levels of dissolved minerals have wreaked havoc with plumbing, water heaters, toilets, ice makers, faucets, etc.

Drinking water supplies contain varying amounts of dissolved minerals. Some relate to their degree of saltiness (chlorides) and others to hardness. These latter are most commonly calcium carbonate and magnesium carbonate. The deposits can be especially bad in water heaters as the precipitates form more quickly in hot water. Unless your water is very soft, you most likely have some white deposits in your coffee maker because of this.

But this discussion of chemistry is rather academic. As in providing medical care, the question arises: why perform the test if you don't anticipate treatment? In other words, unless you're considering some sort of water treatment system, simply accept the condition and enjoy your boat.

jungpeter said:

Hi Bud,

Rather than a facetious, flippant answer to your posted question, which does little than waste bandwidth, I would suggest an honest response.

Regards,

Pete

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Geeze-0-Pete, sorry I tried to inject a bit of humor into this thread. I shall now bow out and leave you chemists to your joy.

Thanks to both of you for your responses. I have two of these tanks in the same condition ,250 gallons each. I was skeptical of the fresh water system when I bought the boat this past summer because of the age of it and the signs of neglect I saw in other systems. The first project I did was install two 50 gallon plastic tanks under the queen size bed in the aft stateroom and changed the fresh water system over to it. I am now am just getting around to servicing the originals tanks. There are no leaks or other issues with the tanks. The plates on the tanks say 1/4 aluminum rated for diesel, which brings up my next question what about if I changed these over to diesel tanks what would those deposits do?
Thanks,
Bud

The CLR disolved the one piece over 24 hours. The piece in the vinegar is still whole. The directions on the CLR bottle says don't use on aluminum. It would nice to find something to treat tank with that could loosen that stuff up.
Bud

Bud said:

The CLR disolved the one piece over 24 hours. The piece in the vinegar is still whole. The directions on the CLR bottle says don't use on aluminum. It would nice to find something to treat tank with that could loosen that stuff up.
Bud

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Bud, my expertise is with irrigation water but I'm not a chemist. The lack of reaction(bubbles=CO2) is indicating it's not a carbonate. I'm at the limit of my knowledge, but I'd likely chase down the aluminum chloride angle. Perhaps a web search is in order. If an acid doesn't work, could you experiment with a alkaloid cleaner and repeat the test? Just ruminating here.