De-sludging holding tanks ? Advice ?

[shorebird]

Holding or septic tanks, when left stationary, divide into 3 layers: the bottom, or "sludge" layer, the middle, liquid layer, and the top layer, referred to as the "crust."
Drop tubes in septic tanks are designed to allow drainage of the liquid layer, without the sludge and crust layers blocking the drainage, but vessel holding tanks left for a significant amount of time can turn to "crust" which is likely coating everything in your tanks. Previous advice may work, particularly the vinegar treatment. Lots of re-hydration and agitation will be the key. BTW, if you have a diesel engine, you may find bigger problems within your tankage and fuel lines than with your holding tank.
Good luck.

[neelie]

Update :

Santa brought me a pair of elbow length rubber gloves - so I got to work opening up the holding tank on Boxing Day.

And surprisingly it was pretty clean and without odors. Thank You Santa!.. Best Christmas present I ever had.

On further investigation, I found

1) the breather thru hull completely blocked solid - which explains why I could only half fill the tank. How a 5/8th inch pipe which only carries gases can be blocked defies belief.

2) The WEMA contents sensor was gummed up with gunk and stuck in the empty position. So, remove, dismantle. clean and check resistance and re-install.

Now everything works as advertised. The Christmas spirit of Peace and Joy returns.

I am attributing the fact there were no odors, to the enzyme/bacteria treatment I added in. Found it in the RV section. I cant yet be sure this was what worked, but in case anyone is interested,its called:

RV DIGEST-IT by Unique ( RV Digest-It Holding Tank Treatment )... I have absolutely no connection with these people other than I randomly selected their product off the shelf.

[DeepFrz]

Peggy recommends that you flush out the vent line every time you pump out the tank.

[neelie]

Originally Posted by DeepFrz

Peggy recommends that you flush out the vent line every time you pump out the tank.

Easier said than done. I cant see how I can do it without assuming some as yet undiscovered yoga position, undoing 2 hose clamps and connecting a garden hose to it.

[thinwater]

Originally Posted by neelie

Easier said than done. I cant see how I can do it without assuming some as yet undiscovered yoga position, undoing 2 hose clamps and connecting a garden hose to it.

From the outside.

You can find those threads with the search function.

----

There are three obvious ways a vent line can get plugged:
* The tanks has been overfilled.
* The vent line is not centered in the lid and thus overflows when heeled.
* The tank sloshes while sailing.

Keeping the tank below 50% is clearly a good idea.

[Hud3]

Yes, if the tank is over-filled and some toilet paper finds it's way into the vent hose, you're in deep doo-doo, to coin a phrase. Toilet paper is the worst clogger.

You can back-flush the vent line by taking the handle out of a toilet plunger and putting the plunger bell over the vent. Hold it tight against the hull and squirt a hose into the handle opening.

[C Skip R]

Try Happy Camper Extreme Cleaner it is a great product designed to clean black water tanks. You can google it.

[jeepbluetj]

Originally Posted by DeepFrz

Peggy recommends that you flush oINGut the vent line every time you pump out the tank.

On my boat, i just hold a hose into the vent while pumping out and the poo sucker sucks right thru the vent.

[US1Fountain]

Originally Posted by neelie

Update :

I am attributing the fact there were no odors, to the enzyme/bacteria treatment I added in. Found it in the RV section. I cant yet be sure this was what worked, but in case anyone is interested,its called:

RV DIGEST-IT by Unique ( RV Digest-It Holding Tank Treatment )... I have absolutely no connection with these people other than I randomly selected their product off the shelf.

I use the marine version of Digest-It. Our marina actually carries both the RV and Marine versions and no one can say whats the difference, other than the label. 2 yrs use and no issues. The marine parts guy says everyone that he has talked into trying it all report back with positive reviews. Odors are the main concern we deal with

[gjordan]

It is possible for bacteria to grow enough in a vent line to plug it, but depending on where the boat was stored before (land or marina) mud dauber wasps are very good at plugging lines even bigger than 5/8 inch. I am glad you had an easy fix. _____Grant.