Deep-Cleaning Water Tanks

[Sea Conquest]

My wife is disgusted by our water tanks so i put 3 inspection ports on our 200 gallon tanks. She was right. They are disgusting. I even discovered that they are leaking (For the ones who are about to tell me to replace them, forget about it. It's a morgan 41. You pretty much have to remove the top of the boat.) The tanks are made of aluminum. I read everywhere to use chlorine but i want to deep clean it so I was thinking muriatic acid (my wife doesn't like that one) or aluminum brightner. For the repair I was hoping to use putty for water tank that I found at pepboys applied to the inside of the tank.

Any suggestions appreciated.

[Tellie]

Can you get to all the areas of your tanks through your 3 inspection ports? If so, elbow grease and a little clorox will take care of it with a few good rinses. I'd pass on the muriatic acid and aluminum brightner. Add a good filter system under the galley sink. Most boats have all kinds of funny stuff floating around and stuck to the walls of their tanks no matter how careful the owner is. You just can't get around the fact that water in dark places makes your tanks a great place to grow stuff.

[bstreep]

Ours were disgusting too. Here was our solution:

Fill and empty the tanks a few times. I used an aquarium pump (750gph) and tubing, to dump it into the bilge (clean, fresh water is always good for the bilge). I filled them up (110 gallons) and added a gallon of bleach to each one (no scent, please!).

Let them sit overnight, then drained and filled them a couple more times.

Now, HERE'S THE SECRET: Use your boat water! We use and then fill the tanks every weekend. Especially with showers, WHERE WE LEAVE THE WATER RUNNING - just like at home. We have lots of friends who attach the dock hose to the boat's water system - and then your tanks suck. It takes about 3 minutes of actual work each weekend to fill the tanks - and what the heck, it makes me rinse off the stainless and deck every weekend too!

[S/V Illusion]

I'd first take a look at the components of the putty you found for water tanks - is is safe for potable water tanks or just "tanks"? It should be easy enough to get at least basic info from the product MSDS.
Regardless of how you plan to disinfect the tank(s), without physical agitation you will never remove the material which adheres to the tank walls. Disinfection is a maintenance action, not a cleaning one.
After you figure out how best to clean the walls, you might also consider peroxide rather than a chlorine solution for disinfection as it will not attack the aluminum, is less sensitive to mixture ratios, has a longer retention time and has greater efficacy at killing bacteria.

[thinwater]

Originally Posted by S/V Illusion

I'd first take a look at the components of the putty you found for water tanks - is is safe for potable water tanks or just "tanks"? It should be easy enough to get at least basic info from the product MSDS.
Regardless of how you plan to disinfect the tank(s), without physical agitation you will never remove the material which adheres to the tank walls. Disinfection is a maintenance action, not a cleaning one.
After you figure out how best to clean the walls, you might also consider peroxide rather than a chlorine solution for disinfection as it will not attack the aluminum, is less sensitive to mixture ratios, has a longer retention time and has greater efficacy at killing bacteria.

Yes, you can mix bleach and ammonia safely, but not right together. Add the bleach to 1/4 tank water, add a little more water then add the ammonia, and then fill. You will use ~ 1/2 the alternative amount of bleach, but it has much better penatrating power and is less corrosive. Many city drinking water systems have gone to chloramine - search it in the web.

We use chloramine on some REALLY nasty cooling tower situations.

Do be careful not to EVER mix bleach and ammonia dirrectly together in a closed space. The fumes are deadly when the products are in concentrate form. The fumes are considerably less than bleach, when dilluted as dirrected above - they disolve into the water.

[LtBrett]

For those of you with fresh water heads, bleach is a no-no in the potable water system. Unless you really like repairing blackwater systems. I use vinegar, but that won't touch bad growth like you describe.

Brett

[Cheechako]

How about renting a small pressure washer and press washing thru the inspection ports? Seems to me this will actually clean them better than relying on chlorine which will kill things but not remove the gunk!

[um saudade]

If the tank contamination is organic rather than a build-up of precipitated chemicals, use a couple of ounces of copper sulfate in each tank. Take care to mix the CuSO4 into slurry before it goes into the tank.
Agitate the tank or simply pump out and back in again to get to all the corners. Let the mixture sit for a couple of days.

While the effects of dumping this mixture into the marina waters is questionable as to toxicity, it would be best to flush at sea where the CuSO4 will instantly be diluted.

Lots of stuff available to patch with. Stick with something that will flex a little when set up.

If you can reach the far corners of the inside of the tank, I suggest you paint the insides with asphalt emulsion. Safe for drinking water tanks, cheap and the best stuff around.
Jerry

[Sea Conquest]

love your idea where can i found that asphalt emulsion and some special preparation

thanks

[CharlieCobra]

Originally Posted by bstreep

Ours were disgusting too. Here was our solution:

Fill and empty the tanks a few times. I used an aquarium pump (750gph) and tubing, to dump it into the bilge (clean, fresh water is always good for the bilge). I filled them up (110 gallons) and added a gallon of bleach to each one (no scent, please!).

Let them sit overnight, then drained and filled them a couple more times.

Now, HERE'S THE SECRET: Use your boat water! We use and then fill the tanks every weekend. Especially with showers, WHERE WE LEAVE THE WATER RUNNING - just like at home. We have lots of friends who attach the dock hose to the boat's water system - and then your tanks suck. It takes about 3 minutes of actual work each weekend to fill the tanks - and what the heck, it makes me rinse off the stainless and deck every weekend too!

Not on a wooden boat. Fresh water causes rot.

[GordMay]

Originally Posted by um saudade

... If you can reach the far corners of the inside of the tank, I suggest you paint the insides with asphalt emulsion. Safe for drinking water tanks, cheap and the best stuff around.
Jerry

Take care to select an aspalt emulsion that is intended for potable water applications.
For instance, many aspalt emulsions sold as roof patching compounds, are specificaly prohibited from contact with drinking water and/or foodstuffs.

[Vino the Dog]

Asphalt emulsion???
Sounds delicious.

[IdoraKeeper]

Originally Posted by CharlieCobra

Not on a wooden boat. Fresh water causes rot.

Thank you Charlie.......that's a really important point.

Todd

[ranger58sb]

SC, you might look for an older thread on here that Peggie Hall (from Raritan) responded to about cleaning tanks AND lines. The short version is fill tanks and lines with chlorine/water, let sit, run through all pipes, repeat with vinegar/water rinse. She suggests proper proportions of each.

-Chris

[Irish rambler]

There's a product called Petropatch which is great for patching leaks in tanks(potable too) available from motor factors. Actually if you mix Bicarbonate of Soda, a tablespoon disolved in warm water per 100 gallons, add it to your tank when filling, let it stand overnight and flush out with no aftertaste, thereafter one teaspoon to a hundred gallons every time you fill keeps the tanks spotlessly clean.
Vinegar @8% is great for cleaning toilets in hardwater areas, pour in 4 pints, pump gently to cover interior fittings/pipes, it disolves Urea acid scale and lime scale in hoses, repeat every 6 months.