Holding Tank not draining

[peghall]

Originally Posted by captain465

Peggy, could you reccomend a product that would remove the material that sticks to the insides of a poly tank? It is becoming difficult to view the tank level due to "stuff" sticking to the tank walls.

That "stuff" is a buildup of the animal fats in waste...it's what also clogs up tank senders. You can spend a lot of money for specialty products to remove it, but none of 'em work any better than a strong solution of any good liquid detergent (a top quality engine degreaser from auto parts stores is great for this) in 3/4 full tank of fresh water...spend a couple of hours tacking a lot to agitate it...then let the solution sit for a few hours. Rinse very thoroughly.

If the tank has an inspection port, add about 20 lbs of hard ice cubes...or if you also have a power washer, using it with detergent will do it a lot faster.

If the tank is "fed" by a sea water toilet, it's possible that there can be some sea water mineral buildup too. The same 12-15% solution of Muriatic (hydrochloric) acid that cleans it out of hoses will also clean it off tank walls. Rinse after about 45-60 minutes.

'Twould be a good idea to make this an annual job instead of waiting till the tank walls become totally opaque.

--Peggie

[Cadence]

Originally Posted by peghall

That "stuff" is a buildup of the animal fats in waste...it's what also clogs up tank senders. You can spend a lot of money for specialty products to remove it, but none of 'em work any better than a strong solution of any good liquid detergent (a top quality engine degreaser from auto parts stores is great for this) in 3/4 full tank of fresh water...spend a couple of hours tacking a lot to agitate it...then let the solution sit for a few hours. Rinse very thoroughly.

If the tank has an inspection port, add about 20 lbs of hard ice cubes...or if you also have a power washer, using it with detergent will do it a lot faster.

If the tank is "fed" by a sea water toilet, it's possible that there can be some sea water mineral buildup too. The same 12-15% solution of Muriatic (hydrochloric) acid that cleans it out of hoses will also clean it off tank walls. Rinse after about 45-60 minutes.

'T would be a good idea to make this an annual job instead of waiting till the tank walls become totally opaque.

--Peggie

Peggie,
Will it work on my arteries? It does make you think about what you eat.

[PassePort III]

Happened to us too so we learned.
If you think the problem is at the bottom of the tank I'd try pourring a lot of baking soda and boiling water in the pump out deck ''fill'', close the cap and let sit for a few minutes then give it a try. If it doesn't work you''ll need some stronger stuff or take a deep breathe.
Good luck.

Bob
s/v PassePort

[kas_1611]

After letting the first chemical solution work away on the blockage we headed out to sea to try our luck. Sadly no joy but I wasn't expecting success first time to be honest.

So the problem now was how to drain the tank of enough liquid to try a second treatment? One of the things about being on a boat is it does work your imagination.

With a sacrificial length of water hose, some duct tape and the old hand powered oil extractor pump we were able to successful syphon the tank virtually empty. Which also had the benefit of stopping the backflow from the tank and hose into the toilet bowl. All this kit has been cleaned and stuck in a plastic bag labelled "**** Happens Kit" for future emergencies.

A double does of chemicals is currently sitting in the tank awaiting a good stir and hopefully a gurgle will happen later today.

[Subtandard]

Been there several times. Urine is seawater produces a precipitate that clogs pipes. I use Hydrochloric acid (also called murriatic acid some places) to dissolve the crud. But use with caution, it can dissolve other things too.

[ranger58sb]

Originally Posted by Subtandard

Been there several times. Urine is seawater produces a precipitate that clogs pipes. I use Hydrochloric acid (also called murriatic acid some places) to dissolve the crud. But use with caution, it can dissolve other things too.

Trac makes a product for cleaning sanitation hoses called Sew Clean, and it's diluted phosphoric acid. See https://trac-online.com/technical-data.

FWIW, Trac told me once that their Barnacle Buster is essentially the same stuff with some anti-marine-growth things added.

-Chris

[SVNeko]

We had the same holding tank setup on our cat. I don't think the chemicals will work. They never seem to. We carried a plumbing snake that coiled up into a case. It was stiff enough to work up into the hose. You need to do this where you can discharge. Start from the deck fitting and push down. If that doesn't work go underneath and snake from the through hull upwards. You may need to change the hose. Calcium can build up and reduce the usable pipe ID to something very small.

[donradcliffe]

Its been over a week since the OP gave us a progress report. Please tell us what worked, or what didn't.

[allendick]

If a pumpout is not available, then perhaps a wet or dry vac would pull up with enough force to clear the blockage if the vent is blocked first. Once the blockage is lifted, flow may resume -- or not -- depending on its nature. Shop vacs are useful for bilge cleaning and other jobs where dirty liquids need to be removed from awkward places. A small one can be had cheaply and most charter companies have one handy. There is bound to be one nearby to borrow.

[Bill_Giles]

I have a piece of conduit, white plastic pipe, about 1/2 in diameter and about a foot longer than the depth of the the tank. I also have one of the snake like drain unblockers. The conduit is put in the tank and it is necessary to feel around to find the tank outlet. Sometimes a little poking around clears the blockage (the end of the conduit is filed to have serrated teeth). Then the drain unblocker is sent down the conduit and of course it is located in the outlet so the snake can be twisted as it follows the outlet pipe. Carefully remove snake and conduit and wash thoroughly (if they come out of the tank together there is less splashing by the free end of the snake). Store carefully, you will need them again!

[kas_1611]

Well the good news is we have achieved drainage

Basically after siphoning off the bulk of the liquids we left a concentrated dose of the chemical agent in the bottom 1/3rd of the tank for 48hrs. On our way towards Lefkas, in the open waters, I hung off the dinghy and held the hose in the seacock while the boss pumped the dinghy pump several times. With a t-shirt stuffed into the seacock I could hear the air gurgling into the tank and we could smell the air from the vent so something was happening.

With a rapid push off the "bung" was removed and with a whoosh a brown cloud was released. With a good flush through we inspected the tank and the walls of the lower 1/3rd were completely clean. So a third dose was made up and the tank filled almost to the brim and left for a further 48hrs before being drained out again in open waters. Tank is now almost completely clean.

So the lessons learnt are keep a "**** happens" kit ready and be prepared to risk a **** shower to clear any blockages. We will also regularly clean both holding tanks with our chemical agent on an annual basis.

Thanks to everyone who has offered advice and tips. Hope this thread will help others with similar problems.

Keiron

[shorebird]

Originally Posted by Pollux

I've heard someone using an air-horn (the handheld type with a compressed air bottle), holding it to the seacock. The pressure from the air, and the vibrations might work wonders.

Scare the sh-- out of the tank. Literally. Have to try that one sometime.

[Kenomac]

Originally Posted by kas_1611

Well the good news is we have achieved drainage

Basically after siphoning off the bulk of the liquids we left a concentrated dose of the chemical agent in the bottom 1/3rd of the tank for 48hrs. On our way towards Lefkas, in the open waters, I hung off the dinghy and held the hose in the seacock while the boss pumped the dinghy pump several times. With a t-shirt stuffed into the seacock I could hear the air gurgling into the tank and we could smell the air from the vent so something was happening.

With a rapid push off the "bung" was removed and with a whoosh a brown cloud was released. With a good flush through we inspected the tank and the walls of the lower 1/3rd were completely clean. So a third dose was made up and the tank filled almost to the brim and left for a further 48hrs before being drained out again in open waters. Tank is now almost completely clean.

So the lessons learnt are keep a "**** happens" kit ready and be prepared to risk a **** shower to clear any blockages. We will also regularly clean both holding tanks with our chemical agent on an annual basis.

Thanks to everyone who has offered advice and tips. Hope this thread will help others with similar problems.

Keiron

Sounds like you gave your boat an enema... Just as I recommended.

Concrapgulations!

[Peter Kokomo]

I have had exactly the same problem twice before, the first time I was able to clear it simply by inserting a metal rod down the 'pump out' opening on the deck. Second time was just a couple of weeks ago, tried the metal rod trick and that didn't work, went under the boat and tried poking a screwdriver up the other way, that didn't help, tried chemicals, that didn't work.
Finally ended up getting a hand operated bilge pump (mounted on a piece of flat wooden board) and connecting a 5m hose to each end. One end I inserted I to the holding tank via the 'pump out' fitting on the deck, twisting the hose around so it fed into the hose at the bottom of the holding tank (the hose that dropes down to the 90 deg. elbow at the through hull fitting) and pushed the hose down until it came up against something solid. The with the tail end of the hose over the side of the boat I started pumping........almost immediately the blockage was cleared and after the nasty brown slick I had created on the ocean surface dissapaited, I flushed the tank and the pump out with seawater and everything has been fine since.

[R2boat]

We have a new to us FP cat with fresh water heads and macerator pump. The holding tank is gravity fed but now will not drain via the valve. My suspect is like so many other posts there is a blockage at the bottom of the tank or at the valve. We managed to pump the tank out via the deck, threaded snake in but could not located the tank discharge hole. Now we have been adding Sew Clean, agitating the contents and draining every few days. So far nothing but what does come back when we pump it out certainly is dirtier than what I would expect.
Now I seem to remember reading where when the tank was installed by FP, occasionally the guy operating the hole saw would allow the plug to fall back in the tank. I would love to think that is not the case with us, so has anyone else heard of that happening....