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Bugoutboat 08-08-2020 09:44

Cleaning Holding Tanks
My wife and I live aboard or Hunter 460. We have been noticing that our sanitary tank is loosing capacity. We have been using K.O. from Rartan to treat our sanitary tank as its an enzyme formula.

What we are noticing is the we are still loosing some capacity. Does anyone have advice on how to clean a boats holding tank so we can regain our capacity?

We found lots of Youtube videos on RV's but really nothing for a boat.

Any advice, and if there is already a thread on this please feel free to point me to it.

Bug Out Boat (BOB):smile:

Tupaia 08-08-2020 10:08

Re: Cleaning Holding Tanks
You don some rubber gloves select a long disposable stick and remove the inspection panel. A strong constitution or a peg for the nose is recommended. Best tip is keep your mouth closed. If you fail to keep your mouth closed you may be able to take solace in that it is probably your own poo.
Have fun - boats who'd have em.

sailorboy1 08-08-2020 10:20

Re: Cleaning Holding Tanks
there are sludge digesters like Noflex

have you tried just using a hose to flush water down the pump out to stir up the tank and the pumping it out?

my holding tank is 19 years old and I have never cleaned it other than the water flushing

S/V Adeline 08-08-2020 10:48

Re: Cleaning Holding Tanks
Cleaning process for a RV works for a boat, as the systems are near identical. For serious tank cleaning, I fill the tanks half full, add cleaning solution of choice, then sail or motor through 2-3ft swells to churn it up. For the RV it is same, just drive it 5-10 miles plenty of stop n goes.
Drain, rinse, should be cleared out. Good luck
S/V Adeline

Bill O 08-08-2020 11:07

Re: Cleaning Holding Tanks
Best time to pump out the tank is just after you return from a good robust sail and everything is shaken up. Then after you pump it out rinse w/water and pump it out again.

If your boat sits in a marina most of the time and pumped out while at the dock, you will get accumulation of sediment in the bottom of the tank.

Depending where you are located, the best time to manually clean out the tank, change fittings or a sender is when it cold out. It will smell much less than during the hotter months.

VanIslandGuy 08-08-2020 11:39

Re: Cleaning Holding Tanks
We just went through this with our aft holding tank. The fix was cheap and easy. The tank was in pretty decent shape as we use Zaal NoFlex religiously but the it still had stuff that was stuck on the insides from before we bought the boat.

1) Start with a completely empty tank.

2) Add 1-2 cups or borax to the tank via the head dissolved with fresh hot water. (Calgon might be better, but it isn't sold locally where I live, Borax is a good/cheap substitute.)

3) Add 1 gallon of liquid OXYGEN Bleach, (not chorline javex), found in the laundry section. (Safe on all metals, won't harm plumbing)

4) Add I cup of liquid Tide or similar laundry detergent.

5) Fill the tank with fresh hot water via the head. (We used the shower head.)

Then wait....

We left it 4 days. 90% or more of what was stuck to the sides of the tank simply dissolved completely. Pumped out and we were good to go.

BlackHeron 08-08-2020 12:36

Re: Cleaning Holding Tanks
We wait until we are offshore and simply flush it over and over again, using the macerator to pump it overboard each time. It's best when it is a little bit sporty to keep it agitated. If not offshore then we do it at pumpout.

It takes hundreds of pumps to fill the tank with our Raritan PH-II manual head but we have an electric raw water deck wash system so we can fill through one or both of the 1" vent hoses which terminate in mushroom through-hull fittings high up. Those cheesy standard screened 1/2" vent fittings are too small and you can't backflush like this with them. Not only does this fill the tank quickly, but it also back-flushes the vents and ensures they are clean and clear of any obstructions.

The only thing we use for cleaning is Raritan CP "Cleans Potties." CP and KO are the only things we ever put into our tank other than sea water and what comes naturally from our body holes. We don't ever use fresh water from the pumpout to flush the tank. If we need to flush with water at pumpout we use our deck wash pump and natural sea water. City water has clorine in it which hurts the good bacteria in your tank. If we want to agitate we can always rock the boat. I have heard ice cubes help in heavy seas. They help scrape the sludge, then melt harmlessly. But again, tap water...

I am sure the Head Mistress will show up soon to add anything that I have missed.

Bugoutboat 10-08-2020 05:59

Re: Cleaning Holding Tanks

Originally Posted by Tupaia (Post 3204078)
You don some rubber gloves select a long disposable stick and remove the inspection panel. A strong constitution or a peg for the nose is recommended. Best tip is keep your mouth closed. If you fail to keep your mouth closed you may be able to take solace in that it is probably your own poo.
Have fun - boats who'd have em.

Lol so true

Bugoutboat 10-08-2020 05:59

Re: Cleaning Holding Tanks
Lol so true

Bugoutboat 10-08-2020 06:00

Re: Cleaning Holding Tanks
We use KO as well and I believe it helps. Over time though we still get some build up. Likely toilet paper is the culprit.

Bugoutboat 10-08-2020 06:01

Re: Cleaning Holding Tanks
This is great advice and will absolutely try this.

Thank you!

Bugoutboat 10-08-2020 06:03

Re: Cleaning Holding Tanks
This is ver good advice. Our marina pumps our boat once a week so stuff never has a chance to build up to bad but over time living on board it just happens. We sail often to keep things churned up. It still builds up though.

Bugoutboat 10-08-2020 06:04

Re: Cleaning Holding Tanks
Have you ever used the spray hose use for cleaning RV holding tanks?

Bugoutboat 10-08-2020 06:05

Re: Cleaning Holding Tanks
Never heard of no flex but am studying it now. Thank you for advice.

wsmurdoch 10-08-2020 07:13

Re: Cleaning Holding Tanks
First shot is Thetford holding tank cleaner which seems to be mostly citric acid and detergent. It does a fair job. I add fresh water to the tank through the pump out deck fitting.

The final solution is to just get on with it and clean the tank. I use this nozzle attached to the end of my anchor wash down hose. [ I don an OB glove on my right arm with a rubber band at my shoulder and a pair of regular exam gloves over the OB glove, open the holding tank inspection port, and go to work pumping out the loosened crud.

By the way, the wand nozzle with its 90 degree nozzle makes a great anchor chain washer.


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