How to clean inside of holding tank?

[mcaswell]

The inside of our holding tank has a coating of "stuff" built up, making it pretty much impossible to see the level. Do you have a suggestion for a cleaning product I could temporarily put in the tank that would be aggressive enough to remove this, without damaging the system?

--Michael

 

[KD3PC]

simply fill the holding tank with ice cubes and enough water for them to bang around, head out for a brisk sail on varying tacks, and by then they have done their job, leaving a nasty liquid to be pumped out.

dave

 

[Peggie Hall HeadMistress]

A gallon of liquid Tide and ice cubes in a full tank of water

You'll need about 10 lbs (an icemaker bucketful) of ice cubes...and use "homemade" ice, not bagged ice..."homemade" cubes are larger and last a lot longer. Put everything in the tank via the pumpout fitting, NOT through the toilet.

Go sailing and tack a lot. If you can, let it sit overnight if you can. Pump out, also run some of the dietergent through any macerator pump. Fill tank again with clean fresh water...pump out and dump again.

That oughta do it.

A cupful of liquid detergent down the toilet 2-3 x/season will prevent the need to do this in the future. Tank should be thoroughly flushed out with clean water 2-3 x/season--and especially in preparation for winter layup--to remove any sludge.

 

[mcaswell]

Wow, thanks... I never would have thought of that!

--Michael

 

[Benny]

After a job well done have yourself a cold one. No offense meant, just could not resist.

 

[Denpaq]

Re: A gallon of liquid Tide and ice cubes in a full tank of water

What if you can't take the boat away from the slip to slosh the ice cubes around in the tank? Is there any way of dislodging the sludge without rocking the boat?

 

[Peggie Hall HeadMistress]

We're only talking about cleaning the SIDES of the tank

The sides of the tank are coated with animal fats and scum that detergent will emulsify and dissolve with or without ice cubes. Sludge accumulation on the bottom is another matter that won't be solved by putting detergent in the tank.

I've posted instructions for flushing out sludge enough times that a search for holding tank sludge should bring it up...if not, I'll post it again.

If you can't take the boat out, why clean the tank until you can? 'Cuz you can't fill up the holding tank with anything till you can take the boat to the pumpout.

 

[Ron20324]

Reach in with a scrub brush?

 

[Denpaq]

I actually have a service that comes every other week to pump the tank out right at my dock. I am a liveaboard. I'm so grateful I've found this forum though. The tank has a ton of sludge against the sides and I will try some detergent next.

 

[Denpaq]

Re: We're only talking about cleaning the SIDES of the tank

Ok, so I've read what I could find here on holding tank maintenance and am duly enlightened. Is there a book? I thought I read something that indicated you have a book, and if so, I must own it! I'll check amazon.com.

My holding tank is 35 gal. and I've only once in the 13 months that I've been using it flushed it with clean water. Lately when I pump the head the smell from the vent is atrocious. From what I understand, and given that my next pumpout is 4 days from now, if I dump 3 quarts of strong cleaning detergent, like Spic N Span, into the tank today, have it all pumped out and then immediately fill the tank with 3 or 4 gallons of water from the deck fill, and also backfill the vent, then have that pumped out at the same time, that this might be a good start toward a new and improved maintenance regime?

 

[Peggie Hall HeadMistress]

One more time...it's not sludge on the sides...

The tank has a ton of sludge against the sides and I will try some detergent next.

But it's even more important to flush sludge out of the tank on a regular basis--and especially in preparation for winter layup--than it is to clean the walls. And your pumpout service is not gonna do it for you!

 

[Peggie Hall HeadMistress]

Yes, there is a book

See the link in my signature below. The chapter "Holding Tank Odor--Odor Out the Vent" should answer most of your questions and I'm glad to answer any others.

Do NOT use powdered detergent! Use only a liquid detergent. Do not use Spic and Span...use liquid Tide or Wisk. Otherwise your plan is a good start on spring recommissioning. The sludge needs to be flushed out too...that will most likely require putting a few gallons of water into the tank more than once...several times, in fact. It's nice to have a pumpout service that comes to you, but that doesn't free you from doing ANY tank maintenance yourself. The sludge should be flushed out 2-3x/season and the vent should be backflushed every time the tank is pumped and/or the boat is washed.

 

[Denpaq]

Will definitely get the book - today

Yes, there is a book...see the link in my signature below.

I don't know if I'm alone on this, but this forum site is always timing out on me, and the link in your signature wouldn't load. I've found the book in my local bookstore, Powell's, the best bookstore on earth, and will go and buy it new today. Can't wait, this is too pressing.

I do understand since reading the forum information the difference between waste on the sides of the tank and sludge on the bottom of the tank. I don't know if I'll be able to affect the sides much, but certainly the other is more important to me because I had no idea of its potential permanence. Thank you for all your help!

 

[gkornreich]

How about adding Calgon too?

Does it help to also add Calgon Water Softener along with the Tide and let it sit for a while?

 

[Peggie Hall HeadMistress]

I don't think so

I don't think it'll hurt anything, but I don't think it'll do any good either. 'Cuz water softeners don't emulsify fats and oils, so it won't contribute anything useful...detergents etc DO suds a lot more in soft water than in hard. Suds don't contribute anything to cleaning either. So unless you just kinda like the idea of soap bubbles and suds wafting from the tank vent, I wouldn't waste the money on Calgon.

 

[gkornreich]

How about Liquid Plumber Foam

I've used Liquid Plumber Foam to eat the grease residue in home plumbing drains. It seems to be safe enough and does not damage the metal or plastic pipes, and does a good job. How about using that for the sludge in a holding tank? I have no idea though of how much to use if it would work...possible enough to break the bank!

 

[Peggie Hall HeadMistress]

Noooo...

Never use a household drain opener in onboard plumbing...there are chemicals in 'em that can damage hoses and other rubber parts in the systems.

But it won't work to dissolve holding tank sludge anyway, 'cuz the sludge isn't grease etc.

Unless the sludge has hardenened into "concrete," water is all that's needed to flush it out of the tank. Put enough water down the pumpout fitting--'cuz that sends the water into the tank at the bottom so it can stir up the sludge and hold it in suspension so it can be pumped out--to cover the bottom of the tank to a depth of 3-4"...pump that out. Repeat...repeat...till you're pumping clean water. Or, if you have a macerator once you have a few inches of water in the tank, turn it on while you leave the water running...when the macerator isn't discharging a brown cloud any more, you're done. You can even use a sea water washdown pump to supply the water.

This should be done at least 2-3x/year, especially in preparation for winter layup.