Crystals forming in fresh water tank of hunter legend 40

[lastlap]

I have been having crystals forming in my fresh water tank and clogging up my filter. The tank is aluminum and at one time I used Clorox to kill bacteria that may have been in the tank. I thought that this may be the problem so I quit using it and started using hydrogen peroxide instead. It seems like the crystals are still forming or else there are a lot of crystals still in the tank. I have only had fresh water in the tank but some was city water from various ports and some was well water. Has anyone else had this problem and what is the fix?

Dave
Last Lap

 

[Don S/V ILLusion]

What color are the 'crystals'?

 

[lastlap]

Hi Don,
The crystals are white and maybe made of calcium but that is only a guess on my part.

 

[Don S/V ILLusion]

The crystals commonly formed in aluminum tanks over many years are aluminum chloride hydrate. Non- toxic but annoying. The use of a hypochlorite disinfectant promotes formation but isn't necessarily the only cause.
Lowering the pH with a weak acid like vinegar will dissolve some of it only if used over a prolonged period. The only way to effectively remove it is through 'brute force' by thoroughly cleaning the tank(s) physically.

 

[lastlap]

Thanks Don, I'm sure brute force will be the way to go. Many thanks for the info.

 

[Terry Cox]

Hi Dave, we have had the same problem with our forward tank over the years. Every season I need to clean out the shutoff valve at the tank and also the screen filter that protects the water pump. Usually good for a season.

 

[lastlap]

Hi Terry, thanks for the message. I figured it had been happening to a lot of folks and not just me.

 

[JamesG161]

Aluminum Chloride Hydrate is the corrosion product of Aluminum and dissolved Chlorine gas for purification. It forms from the un-anodized aluminum metal ( don't let you eyes glaze over). I wouldn't remove it at all! It is like a "scab" forming on a wound. The typical spots you will find it is on the aluminum welds, since the weld is not anodized ( method used to protect Aluminum in a pre-corroded passive state). As my mother told me, "Don't pick at your scab!!"

Every season I need to clean out the shutoff valve at the tank and also the screen filter that protects the water pump.

Is a good idea, for possible lose crystal capture!

But if you want to dissolve it or scrub it and remove the tank's protective barrier...

Use a mix of vinegar or CLR® with cheap vodka (what a waste). The alcohol dissolves the AlCl3. You can use a cheaper alcohol like rubbing, denatured or methanol, but you must rinse you tank a minimum of 3 times to remove the bad stuff in them. Since the bottom welds are normally the culprit, just cover them with a very dilute mix of the acid/alcohol mix. If you give me your tank size I can suggest a good formula.

A moderately expensive alternative is to buy a "on boat" water maker that makes water form the sea/fresh water called Reverse Osmosis (RO water. Read most bottled water labels). RO water is purified, desalinated water like rocky mountain spring water.

There are other "poor man" methods of removing Chlorine from water, if you are interested.
Jim...

 

[lastlap]

Hi Jim,
That's an interesting cure for the crystals. I hate to waste vodka so I will probably just continue to clean out the tank when it needs it by the "wash and drain" method. Interesting point about not wanting to remove the protective "scab". I'm not sure of the measurements but the tank is 100 gallons.

Dave

 

[JamesG161]

If your tank is about the same size as my 100 gallon, then it is roughly 36"x24"x10". If most of the crystals are in the bottom weld and up the corners about 20 gallons (20%) would cover most of the crystals. After reading that you do "wash/drain/rinse" procedure, I would use 1 gallon of 5% vinegar and 1 quart of denatured alcohol (buy in Home Center). Pour the vinegar and alcohol in empty tank, then fill to 20% with water (this is just a mixing technique, not critical). Let soak over night. My guess is no AlCl3 will be left. Drain and rinse a few times. Not for toxicity, but who wants to have their water taste like salad dressing.

If you fill from a "hard water" source, then it may be Calcium. Use CLR® instead of vinegar to remove Calcium and Iron, no alcohol needed.
http://www.thecarycompany.com/containers/facility/clr-multisurface.html

This is a way to test if it is Aluminum versus Calcium crystals.

If it is Aluminum crystals are at the weld area, then you can prevent it next year by filling your tank through a Carbon active water filter.
This is the cartridge and the filter is shown in the "bought together" section.
http://www.amazon.com/DuPont-WFPFC8...46408552&sr=1-1&keywords=carbon+water+filters
Not too big to install on your boat for transient water sources that purify them too.
This will all but eliminate Chlorine in your fresh water tank.

I would stop using bleach to "sanitize your tank" , but use this in your tank.
http://www.amazon.com/Hydrogen-Peroxide-3%-1-gallon/dp/B001F28XH4/ref=sr_1_26?ie=UTF8&qid=1446410536&sr=8-26&keywords=hydrogen+peroxide
The peroxide disinfects and leaves H2O and Oxygen behind. That gallon above will do your 100 gal tank.

If you are worried about bacteria without Chlorine then use this.

http://www.amazon.com/Potable-Aqua-...id=1446406648&sr=8-2&keywords=water+treatment
I have these onboard in the emergency box.

If you are making a Bahama trip, then diesel is cheaper than water. Use this on board Reverse Osmosis system.
http://www.amazon.com/Katadyn-Power...446412385&sr=1-2&keywords=desalination+system

A bit pricey, but will solve all your Crystal, disinfection, and water problem from transient sources. I use RO to make coffee using this system in my office and fill sports bottles too. I have been thinking about installing this on the dock and filling my tank over a few day or over night if I rig a full tank shut off.

http://www.lowes.com/pd_129808-47429-WHER25___?storeNumber=2350&Ntt=reverse+osmosis+system&selectedLocalStoreBeanArray=[com.lowes.commerce.storelocator.beans.LocatorStoreBean@197c197c]&pl=1&productId=50139856

Long answer for a simple question, but remember, your aluminum tank is dissolving away.
Jim...

PS: Never mix an acid, like vinegar or CLR®, with bleach. You will get toxic Chlorine gas in your face.

 

[lastlap]

Thanks for all the good info. I know many readers will benefit from this advice as well as me.
Dave