- Joined
- Jun 25, 2008
- Messages
- 10,104
- Location
- Australia
- Vessel Name
- Now boatless - sold 6/2018
- Vessel Make
- Had a Clipper (CHB) 34
Yes. Been there...done that. I'm afraid it's cactus. Had to replace mine for same reason just a few months ago.
black water tank won't pump out
- Thread starter Teresa G
- Start date
The friendliest place on the web for anyone who enjoys boating.
If you have answers, please help by responding to the unanswered posts.
If you have answers, please help by responding to the unanswered posts.
Yes. Been there...done that. I'm afraid it's cactus. Had to replace mine for same reason just a few months ago.
I've been pondering the plugged vent thing.
While I understand how plugged vent might prevent emptying a tank I wonder how the toilet would work in that situation too.
Then there is the question of wouldn't the tank simply pull air through the toilet itself if the vent were plugged and the tank being pumped?
Our Jabsco not-so-Quiet-flush only has a single joker valve and a small standing column of water to pull through...don't these tank pumps have enough suction to pull air through that?
I believe that the tank might be sludge filled...
One trick RV'rs use to overcome a sludged tank is to use a combination of fabric softener and Tide dishwater detergent in the tank to soften the goo. That and a big pile of ice and a ride on a bumpy road helps break everything up so it can be drained. I guess the trick would be getting the ice into the tank on a boat...
In an RV, it's easy.
Just curious,
Bruce
While I understand how plugged vent might prevent emptying a tank I wonder how the toilet would work in that situation too.
Then there is the question of wouldn't the tank simply pull air through the toilet itself if the vent were plugged and the tank being pumped?
Our Jabsco not-so-Quiet-flush only has a single joker valve and a small standing column of water to pull through...don't these tank pumps have enough suction to pull air through that?
I believe that the tank might be sludge filled...
One trick RV'rs use to overcome a sludged tank is to use a combination of fabric softener and Tide dishwater detergent in the tank to soften the goo. That and a big pile of ice and a ride on a bumpy road helps break everything up so it can be drained. I guess the trick would be getting the ice into the tank on a boat...
In an RV, it's easy.
Just curious,
Bruce
ranger58sb
Guru
I reckon we'll maybe do that, whenever I get around to it. The actual replacement process should be fairly easy, even if slightly messy for a few minutes. Although I might at the same time replace the discharge hose from the holding tank, simply because I could.
Anyway, the replacement pump isn't expensive. We replaced the fishbox macerator pump (same model) already, relatively easy... and even that turned out to be unnecessary. Turned out to be an incorrectly diagnosed issue: a hard clog (fish scales and so forth) at the thru-hull. But at least that motor would run. So I've already got one decent spare...
-Chris
The toilet will work with a plugged vent up to a point. How do I know??
Our vent was plugged when we first purchased our boat. We did not realize at first because we were offshore for the first several days returning to the northeast from Florida, and just discharged waste. Once back we switched to the holding tank. Over the next couple of weeks the electric head operated but it became more difficult to close the bathroom door. Then the tank level sensor stopped working. Time to take a look at the FG holding tank. It was pumped up and inflated such that it was putting enough pressure on the floor above to interfere with the door, and squeezing the connectors to the tank sensor. Just glad the problem was discovered before we had a SOL explosion!!! So you can definitely pump in when you can not pump out, but it is not advised!!!
Our vent was plugged when we first purchased our boat. We did not realize at first because we were offshore for the first several days returning to the northeast from Florida, and just discharged waste. Once back we switched to the holding tank. Over the next couple of weeks the electric head operated but it became more difficult to close the bathroom door. Then the tank level sensor stopped working. Time to take a look at the FG holding tank. It was pumped up and inflated such that it was putting enough pressure on the floor above to interfere with the door, and squeezing the connectors to the tank sensor. Just glad the problem was discovered before we had a SOL explosion!!! So you can definitely pump in when you can not pump out, but it is not advised!!!
While I understand how plugged vent might prevent emptying a tank I wonder how the toilet would work in that situation too.
Flushing a toilet against a blocked vent will pressurize the system. Opening the deck pumpout cap when the tank is pressurized will release a geyser. The first clue that the system is becoming pressurized is a toilet that starts "burping" and spitting up when you flush it.
Then there is the question of wouldn't the tank simply pull air through the toilet itself if the vent were plugged and the tank being pumped?
It'll try to pull in air from anywhere it can, but the air flow through the toilet isn't enough to prevent a strong pumpout from pulling some vacuum...iow, it may be able to pull the waste out, but very slowly with pressure that can suck tank walls in. A macerator pump doesn't have enough suction to pull much of anything out against a blocked vent. In fact, any hissing in a toilet bowl is a strong indication of a blocked vent.
Our Jabsco not-so-Quiet-flush only has a single joker valve and a small standing column of water to pull through...don't these tank pumps have enough suction to pull air through that?
If the joker is so worn that the slit has become a hole, the pumpout can empty the tank, but very slowly while it pulls on the tank walls. In fact, if the boat/toilets sit unused long enough, the pressure in the system can escape through the toilet...allowing the deck pumpout cap to be opened without releasing a geyser. But it's unlikely the toilet(s) on a liveaboard will sit unused long enough to do that.
As with most things, prevention is a lot easier--and in the case of a blocked tank vent, more pleasant--than cure. And the simplest way to prevent a blocked holding tank vent is to replace the "vent" thru-hull (which is actually designed for fuel tank vents, but boat builders use the same thru-hulls on all vent lines) with an open "bulkhead" or "mushroom" thru-hull that you can stick a hose nozzle up against and backflush the vent line every time you wash the boat and/or pump out.
I believe that the tank might be sludge filled...
If you've never flushed out the tank, there could be an inch or two of sludge on the bottom, but no more...and not even that much unless you use a lethal chemical tank product that kills the bacteria needed to break down and liquify solids and TP. Unlike RVs, the contents of marine tanks is mostly flush water...RV toilets use only enough to rinse the bowl as the the contents slide into the tank directly below it--just a pint or two...and most RVers do use lethal chemicals, primarily Thetford products. So 90% of the contents of an RV tank IS sludge. Plus, RV tanks are literally dumped out a port in the bottom of the tank...no rinsing--RVers are even lazier about tank maintenance than boat owners...leaving what's known as the "poop pyramid" to build up in the tanks. When the RV sits between trips, the sludge turns to concrete. RVers don't do anything to PREVENT it, but they do get creative in their efforts to cure it with the least amount of effort possible.
Use a bio-active or other tank product that doesn't kill all the bacteria needed to break down and liquify solids and TP...rinse out your tank 2-3 x a year--and especially before winter or any other extended layup--and sludge won't be a problem.
And btw, joker valves should be replaced at least every two years if you want them to be a one-way valve instead of just a piece of rubber that partially blocks the flow from the toilet.
Peggie
http://www.amazon.com/New-Get-Rid-Boat-Odors/dp/1892399784/
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
Flushing a toilet against a blocked vent will pressurize the system. Opening the deck pumpout cap when the tank is pressurized will release a geyser. The first clue that the system is becoming pressurized is a toilet that starts "burping" and spitting up when you flush it.
Then there is the question of wouldn't the tank simply pull air through the toilet itself if the vent were plugged and the tank being pumped?
It'll try to pull in air from anywhere it can, but the air flow through the toilet isn't enough to prevent a strong pumpout from pulling some vacuum...iow, it may be able to pull the waste out, but very slowly with pressure that can suck tank walls in. A macerator pump doesn't have enough suction to pull much of anything out against a blocked vent. In fact, any hissing in a toilet bowl is a strong indication of a blocked vent.
Our Jabsco not-so-Quiet-flush only has a single joker valve and a small standing column of water to pull through...don't these tank pumps have enough suction to pull air through that?
If the joker is so worn that the slit has become a hole, the pumpout can empty the tank, but very slowly while it pulls on the tank walls. In fact, if the boat/toilets sit unused long enough, the pressure in the system can escape through the toilet...allowing the deck pumpout cap to be opened without releasing a geyser. But it's unlikely the toilet(s) on a liveaboard will sit unused long enough to do that.
As with most things, prevention is a lot easier--and in the case of a blocked tank vent, more pleasant--than cure. And the simplest way to prevent a blocked holding tank vent is to replace the "vent" thru-hull (which is actually designed for fuel tank vents, but boat builders use the same thru-hulls on all vent lines) with an open "bulkhead" or "mushroom" thru-hull that you can stick a hose nozzle up against and backflush the vent line every time you wash the boat and/or pump out.
I believe that the tank might be sludge filled...
If you've never flushed out the tank, there could be an inch or two of sludge on the bottom, but no more...and not even that much unless you use a lethal chemical tank product that kills the bacteria needed to break down and liquify solids and TP. Unlike RVs, the contents of marine tanks is mostly flush water...RV toilets use only enough to rinse the bowl as the the contents slide into the tank directly below it--just a pint or two...and most RVers do use lethal chemicals, primarily Thetford products. So 90% of the contents of an RV tank IS sludge. Plus, RV tanks are literally dumped out a port in the bottom of the tank...no rinsing--RVers are even lazier about tank maintenance than boat owners...leaving what's known as the "poop pyramid" to build up in the tanks. When the RV sits between trips, the sludge turns to concrete. RVers don't do anything to PREVENT it, but they do get creative in their efforts to cure it with the least amount of effort possible.
Use a bio-active or other tank product that doesn't kill all the bacteria needed to break down and liquify solids and TP...rinse out your tank 2-3 x a year--and especially before winter or any other extended layup--and sludge won't be a problem.
And btw, joker valves should be replaced at least every two years if you want them to be a one-way valve instead of just a piece of rubber that partially blocks the flow from the toilet.
Peggie
http://www.amazon.com/New-Get-Rid-Boat-Odors/dp/1892399784/
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
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I'm surprised that enough pressure to bulge the tank enough to raise the cabin sole wasn't enough to cause an eruption through the toilet. The joker valve wouldn't stop it...that much pressure would turn joker valve inside out. It's happened to more than one person.
Peggie
http://www.amazon.com/New-Get-Rid-Boat-Odors/dp/1892399784/
"If you can't explain it to a six year old, you don't completely understand it yourself." --Albert Einstein
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I went back and re-read the original post. I mistakenly thought that the tank had been sitting filled since the fall of 2015...
Clearly, if the boat had been in use, as it was, sludge isn't the issue.
Maybe the tank wasn't being used and it's actually empty?
Bruce
Clearly, if the boat had been in use, as it was, sludge isn't the issue.
Maybe the tank wasn't being used and it's actually empty?
Bruce
***Problem Solved***
First I want to thank you all. All of the information you sent helped me understand the process better and I sounded somewhat more knowledgeable when addressing the guys working on the situation. I knew what questions to ask and how to interpret their answers. And they were grateful that I was able to speak intelligently with them. And thank you for being patient while we worked through the process of 'elimination'. In the end the answer is **IT WAS NEVER MY BOAT***. It was the marina pump out. Here is what I learned. After spending hours and days on my boat with the marina I got a referral through one of the responses to my post. He recommended a local man who somewhat specializes in this area. Within an hour of being here he tested the marina pump, which hadn't been done. Their main pumpout at the fuel dock that ties into the city sewer measured <12 iov(inches of volume) and their mobile cart tested at <10 iov. As was explained to me a good boat pump out should test between 25 and 30 iov. Thankfully NO HOLES WILL BE CUT IN MY BOAT. The marina has been very responsive. They have already made plans to increase their pump power and adding a vacuum guage so the dockmaster can more easily monitor its effectiveness. A happy ending. Hooray The mans name is John Bragg 386-916-0718 and he pretty much works the St Johns river area. I can recommend him.
First I want to thank you all. All of the information you sent helped me understand the process better and I sounded somewhat more knowledgeable when addressing the guys working on the situation. I knew what questions to ask and how to interpret their answers. And they were grateful that I was able to speak intelligently with them. And thank you for being patient while we worked through the process of 'elimination'. In the end the answer is **IT WAS NEVER MY BOAT***. It was the marina pump out. Here is what I learned. After spending hours and days on my boat with the marina I got a referral through one of the responses to my post. He recommended a local man who somewhat specializes in this area. Within an hour of being here he tested the marina pump, which hadn't been done. Their main pumpout at the fuel dock that ties into the city sewer measured <12 iov(inches of volume) and their mobile cart tested at <10 iov. As was explained to me a good boat pump out should test between 25 and 30 iov. Thankfully NO HOLES WILL BE CUT IN MY BOAT. The marina has been very responsive. They have already made plans to increase their pump power and adding a vacuum guage so the dockmaster can more easily monitor its effectiveness. A happy ending. Hooray The mans name is John Bragg 386-916-0718 and he pretty much works the St Johns river area. I can recommend him.
TheTuftedPuffin
Member
- Joined
- Sep 7, 2017
- Messages
- 21
- Location
- United States
- Vessel Name
- Yet to be Named. PO - Serendipity
- Vessel Make
- Puget Trawler 37
Another SOL Story
Thanks to all who posted on this thread. I just went through a SOL situation on my friend's American Tug 41 "Admiralty". After reviewing this thread I now understand why.
Thanks to all who posted on this thread. I just went through a SOL situation on my friend's American Tug 41 "Admiralty". After reviewing this thread I now understand why.
MYTraveler
Guru
Your question has probably been answered, but in case not, this happened to me once: Neither the overboard pump nor then dockside (pumpout station) pump would work. Turns out that a delivery captain had clogged the vent line (by completely overfilling the holding tank), so when trying to pump out with the onboard pump (and with the deck cap in place, as it normally is), the clog prevented the onboard pump from sucking anything out. Similarly, with the deck cap open the pumpout station wouldn't work. I finally got the idea of putting water into the vent cap and using the on board pump at the same time. Worked fine, until I put the deck cap back in place. Finally it dawned on me that the vent line was clogged.
