Holding tank plugged

[All U Get]

Hi all,

A fellow cruiser recently bought a boat and is now here in the Exumas. Their head pumps to the tank then the hose from the bottom of the tank splits to the mascerater/overboard and the deck plate for a pump out. They thought the tank was empty before crossing and they tried pumping with the mascerater which burned out. He separated the hose coming from the tank and using the new mascerater and a section of additional hose pumped a bucket of water overboard clearing hose and seacock.

Now he tried snaking a wire into the hose towards the waste tank discharge fitting (dangerous if you free the plug) but couldn’t get the wire snake passed the 90 degree fitting. After reconnecting the hoses, we tried pulling suction with the mascerater again but stopped after hearing the mascerater struggle not pulling anything from the tank.

I’m thinking the PO left solids in the tank harden and now it’s plugged tight. The tank is full and the vent hose could be blocked also. There isn’t any access to the top of the tank, it’s under the battery box. Any thoughts? I thought holding a random orbital sander against the tank might vibrate it loose.

 

[Calif. Ted]

I just had to replace a couple sections of hose and a wye, absolutely rock hard solid calcium build up just from passage of seawater, I don't think you can break it loose. Might it be just the 90 degree elbow ?

 

[dlochner]

There are 2 kinds of 90* plumbing elbows, a sweep and an elbow. The sweep has a larger radius and it allows for better flow of the stuff that flows through it. A straight 90* elbow will clog. Stuff hits the corner and instead of sliding through, it clogs and blocks the hose.

The stuff could be calcium build up from seawater, could be something that went into to the holding tank without being eaten first, could be some incompatible TP.

If you can get some Muriatic acid and if you can easily pour some into the hose from the outlet side, you may be able to clear the blockage. If it is calcium carbonate, the acid will dissolve it. The acid will not cause any major issues with the hose. If you can go this route, be prepared, the when the acid hits the calcium carbonate it will bubble and foam a great deal potentially making a mess.

If there is access to the top of the tank and if the boat has a Whale Gusher bilge pump, it may be possible to jury rig the WG pump to empty the tank. The Whale gusher can handle all kinds of junk.

If the tank can be emptied, by passing the tank and going to a direct overboard discharge may be the best alternative until a more permanent solution can be found. Of course that means legal use fo the head in some places will be prohibited.

Good Luck!

 

[JamesG161]

I’m thinking the PO left solids in the tank harden and now it’s plugged tight

or something plastic!!!

If the Hold tank has a working level sender, loosen it and be prepared for an ooze.
Nothing oozing, then open it enough to act as an air vent in.
Now try to pump out again.

Still no success, remove the sender and then you can snake the exit.
Jim...

 

[Terry Cox]

The tank is full and the vent hose could be blocked also

Similar problem when we purchased our boat in 2002. Wrote an article about it here: https://hunter.sailboatowners.com/mods.php?task=article&mid=45&aid=6003&mn=42

 

[Peggie Hall HeadMistress]

First thing I'd do is clear the vent, 'cuz a blocked tank is the most common cause of everything you're describing...'cuz if there's no source of air to replace contents as they're pulled out, the pumpout or macerator pump will pull a vacuum. Continuing to try can easily burn out a macerator motor.
The two most common locations for a vent blockage are the vent thru-hull and the other end of the vent line--both that end of the hose and the vent fitting on the tank. Start with the vent thru-hull. Use a screwdriver, ice pick--whatever works--to clean it out...if there's a screen in it, knock it out...screens become clogged with dust, pollen and corrosion, causing more problems than they solve or prevent.
Next, open the deck pumpout cap to relieve any pressure in the tank...then remove the vent line from the tank. Scrape out the tank fitting and that end of the vent line, put the vent line back onto the fitting.
If a blocked vent was your only problem, you should be able to pump out or dump using a macerator now. If it wasn't, you have a clogged tank discharge line. Muriatic acid may or may not dissolve it, prob'ly will require several applications an hour or two apart. Fwiw, it would literally take YEARS for sludge to build up in a tank to a depth that would completely block the discharge port.

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

 

[All U Get]

Thanks folks, I’ll get him to work on the vent fittings first. He did mention pulling the vent hose off, but I don’t know if he cleared the fittings.

There are 2 kinds of 90* plumbing elbows, a sweep and an elbow. The sweep has a larger radius and it allows for better flow of the stuff that flows through it. A straight 90* elbow will clog. Stuff hits the corner and instead of sliding through, it clogs and blocks the hose.

The stuff could be calcium build up from seawater, could be something that went into to the holding tank without being eaten first, could be some incompatible TP.

If there is access to the top of the tank and if the boat has a Whale Gusher bilge pump, it may be possible to jury rig the WG pump to empty the tank. The Whale gusher can handle all kinds of junk.

Good Luck!

Straight 90 and uses seawater, I’ll check on a sending unit access from the top but I remember it being tightly built in(aren’t they all).

First thing I'd do is clear the vent, 'cuz a blocked tank is the most common cause of everything you're describing...'cuz if there's no source of air to replace contents as they're pulled out, the pumpout or macerator pump will pull a vacuum. Continuing to try can easily burn out a macerator motor.
The two most common locations for a vent blockage are the vent thru-hull and the other end of the vent line--both that end of the hose and the vent fitting on the tank. Start with the vent thru-hull. Use a screwdriver, ice pick--whatever works--to clean it out...if there's a screen in it, knock it out...screens become clogged with dust, pollen and corrosion, causing more problems than they solve or prevent.
Next, open the deck pumpout cap to relieve any pressure in the tank...then remove the vent line from the tank. Scrape out the tank fitting and that end of the vent line, put the vent line back onto the fitting.
If a blocked vent was your only problem, you should be able to pump out or dump using a macerator now. If it wasn't, you have a clogged tank discharge line. Muriatic acid may or may not dissolve it, prob'ly will require several applications an hour or two apart. Fwiw, it would literally take YEARS for sludge to build up in a tank to a depth that would completely block the discharge port.

--Peggie
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein

I stood back when I saw he had disconnected the hose from the bottom of the tank leaving the elbow and about a two foot piece of hose. We added another three feet to this just in case the plug moved when he was snaking it. I will pass along the info.

Nobody mentioned a barf bag.

I have some Raritan CH that we could fill the hose with after we try opening the vent.

 

[jibes138]

Can you remove the vent fitting then a small diameter tubing and a water pump might be able to remove the liquids from the tank through the vent hole. If the tank can be tilted after all the liquid is out put a 2x4 under the discharge end to maybe allow removal of the discharge fitting?

 

[All U Get]

Can you remove the vent fitting then a small diameter tubing and a water pump might be able to remove the liquids from the tank through the vent hole. If the tank can be tilted after all the liquid is out put a 2x4 under the discharge end to maybe allow removal of the discharge fitting?

I can’t remember that much room around the tank but I’ll check.

 

[Ron20324]

Well, gee, All U Get... this really sucks. Or, since it does not, did you try blow? Stick a shop vac exhaust into the deck fitting to clear the stoppage. Then see if you can feel the breeze out the vent.

One time back at the slip, the honey boat could not empty the tank. Blew water into the deck fitting cleared the blockage, and I figured the little pads some female flushed had all sunk and blocked the tank outlet hole.

 

[All U Get]

Well, gee, All U Get... this really sucks. Or, since it does not, did you try blow? Stick a shop vac exhaust into the deck fitting to clear the stoppage. Then see if you can feel the breeze out the vent.

One time back at the slip, the honey boat could not empty the tank. Blew water into the deck fitting cleared the blockage, and I figured the little pads some female flushed had all sunk and blocked the tank outlet hole.

Good thought with back pressure, talked to the owner to clear the vent first.

 

[All U Get]

So with the first attempt at a dockside pump out not working , vinegar and baking soda was added to soften the plug. The following day the pump out worked, lucky them.

 

[shemandr]

You're a good mate to put so much time in on someone's else's sanitation problem.

 

[JamesG161]

vinegar and baking soda

I bet the vent smell was wonderful as the CO2 bubbled away!!
Jim...

 

[Ron20324]

..., vinegar and baking soda was added to soften the plug. The following day the pump out worked, lucky them.

Remember those little boats that came in cereal boxes? Fill them with baking soda, and as it reacted to the water, it would propel the boat.

 

[shemandr]

I bet the vent smell was wonderful as the CO2 bubbled away!!
Jim...

Gives a new odor to the JB tune Volcano.

 

[All U Get]

Remember those little boats that came in cereal boxes? Fill them with baking soda, and as it reacted to the water, it would propel the boat.

That’s why the navy uses beans, eh?