Waste Tank Vent Hose Smell

[flboy]

Hey Everyone

The vent hose for our waste tank smells quite badly. The hose connects to the top of the waste tank and routes through a cabinet and connects to the metal vent. The cabinet the hose runs through is pretty much not usable since it smells so bad in there. When we bought the boat the hose was just a simple clear hose and I replaced it with the basic sanitation hose from the local marine supply store and it didn't help at all. I was thinking about buying a higher grade sanitation hose online and see if that helps. I just wanted to see if anyone had any suggestions for the best hose or ideas on why it smells so bad. I've attached a pic of the hose I bought and installed recently.

Thanks in advance for any suggestions/ideas

 

[SteveK]

do you have a filter in the line, or is the hose one lenght from tank to thru hull.
I ask because I installed a new filter and well it got wet, the gas then escaped. Now one complete hose and no smell

 

[RT Firefly]

Greetings,
Mr. fl. Your tank doesn't have enough ventilation and the contents have gone anaerobic. Check the through hull for blockage and invest in a microbial tank treatment. You want a community of LIVING "bugs" in the tank. You may also need a large vent hose. What size is the one in the picture?


Are you sure the tank is not cracked somewhere or a fitting isn't leaking?

 

[flboy]

The hose is one length from fitting to vent, no filters. Inner diameter of the hose is 5/8" and I do use a microbial treatment and that does help. Definitely noticed it's much worse when the tank is near full or I haven't added a treatment in a while. I don't think there are any cracks or or leaks as I don't see anything in the bilge. The smell is the worst in the cabinet that the hose runs through.

 

[Bacchus]

What type is the thru hull? It looks to be a 90* fitting?
Best practices per Peggie the " HeadMistress" is 1 " hose to a straight mushroom type thru hull. That allows back flushing w a hose periodically to make sure it stays open. Routing the hose as short and direct as possible also helps.
Many, myself included, have had very good results with NoFlex treatment.
To check for permeating soak a clean rag in HOT water and wrap the hose with it. Leave it in place for ?? Hours. Then take a smell after removing. If so replace it.
Peggie will likely chime in with her expertise. Her book is a great resource and worth more than the cost to correct or avoid head issues.

 

[flboy]

Both fittings are 90 degree, upgrading to a larger hose may be difficult since it routes through that hole as seen in the pic and I'll need to see if there is enough room to widen that hole for the larger hose. Straight fitting on the tank itself isn't possible since the floor piece goes right above it (the tank sits directly below the floor) but would be possible on the side that vents out of the boat.

 

[Comodave]

Use Raritan Sani/Flex hose. It doesn’t permeate. You will have to go up in size to 1” or 1 1/2” but that is a good thing as more air will get into the tank and promote aerobic bacteria that is your friend. Change the through hull fitting to an open mushroom type so you can backflush the vent. And if possible add a second vent to the other side of the boat so even more air can get into the tank. I am putting in a Groco Sweetank in my boat this winter since I cannot get a second vent or larger vent than 5/8”. The Sweetank pumps air into the tank to promote aerobic bacteria. I put one in a previous that had an 80 gallon holding tank. After I put it in I never added any chemicals whatsoever and had absolutely no smell.

 

[Comodave]

Both fittings are 90 degree, upgrading to a larger hose may be difficult since it routes through that hole as seen in the pic and I'll need to see if there is enough room to widen that hole for the larger hose. Straight fitting on the tank itself isn't possible since the floor piece goes right above it (the tank sits directly below the floor) but would be possible on the side that vents out of the boat.

If you can’t go to a larger hose then go with the Sweetank and I would replace the vent hose again as one it has permeated it can’t be saved. That should fix your issues. An absolutely no filter in the vent hose.

 

[SteveK]

Why go larger hose, curious. Between use a 1/4 " will vent. A sudden inflow of wastemay take longer to balance. IMO.
If the thru hulls is not plugged it should be good. Is there a screen with salt crusted.

 

[Larry M]

...Definitely noticed it's much worse when the tank is near full or I haven't added a treatment in a while...

There seems to be an additional issue besides the hose. If the smell is worse when the tank gets near full, check for cracks or leaks where the vent attaches to the tank. The amount of odor break through on the hose isn’t going to change on how full the tank is.

 

[kchace]

The hose is one length from fitting to vent, no filters. Inner diameter of the hose is 5/8" and I do use a microbial treatment and that does help. Definitely noticed it's much worse when the tank is near full or I haven't added a treatment in a while. I don't think there are any cracks or or leaks as I don't see anything in the bilge. The smell is the worst in the cabinet that the hose runs through.

The hose may smell, but if you notice that the smell is much worse when the tank is near full, then you also have something else going on. I would suspect there is a small vent LEAK into the cabinet in question.


Ken

 

[Bacchus]

The purpose of the tank vent is twofold.
1 - to prevent tank positive or negative pressure by allowing air outflow when tank is filling and inflow when pumping out. In that case a small dia hose should suffice.
2 - to allow sufficient air to exchange with vapors above the liquid to enable aerobic breakdown which has a much more pleasant smell. Without sufficient air /O2 the breakdown turns anaerobic and smell will be less than desirable. A larger dia vent is generally required to fo this and is more important as the distance increases. Any turns and dips can interfere with airflow.
On a prior boat adding a second straight mushroom thru hull vent on the.opposite side of the hull corrected a poorly vented situation and associated smell.
For more detail see the Holding Tank Aeration project on this link.
https://dkloeber.wixsite.com/bacchus/projects-pg-2
I have been very satisfied with the results for about 10 - 20% of the cost of a Groco Sweettank system.

 

[BruceK]

Can`t be permeated hose,unless the replacement hose he fitted permeated instantly he fitted it, which seems unlikely.

 

[Comodave]

Why go larger hose, curious. Between use a 1/4 " will vent. A sudden inflow of wastemay take longer to balance. IMO.
If the thru hulls is not plugged it should be good. Is there a screen with salt crusted.

A 1/4” vent would cause way more problems than he has now. The vent serves several purposes. It needs to allow pressure inside the tank to equalize during filling and during emptying the tank. With a really good pump out and a 1/4” bent you could collapse the holding tank if the unusually small vent may not pass enough air into the tank in time for it not to collapse. I say could because I would not be willing to chance it on my holding tank. Also a 1/4” vent would clog much more easily than even a 5/8” vent. Another problem with undersized vents is air flow during everyday operations. It will not allow enough air into the tank to encourage aerobic bacteria to grow, rather it will encourage anaerobic bacteria to grow. Anaerobic bacteria is what smells. This will make your problem way worse.

 

[HeadMistress]

I need more information before I can offer any advice (an idea the rest of y'all might also consider).



1. Is your problem odor from the tank that's escaping out the tank vent? Or do you have a stinky vent line (hose) INSIDE the boat?


2. Iow, is your odor INside the boat or are you just gassing everyone within 50 yds of you OUTside the boat?



--Peggie

 

[Taras]

Curious if anyone uses toilet cleaning products that contain Bleach and if so what that does to the “natural “ state of the tank. I’m assuming the bleach would kill off everything and then the stink would return.

 

[Giggitoni]

Curious if anyone uses toilet cleaning products that contain Bleach and if so what that does to the “natural “ state of the tank. I’m assuming the bleach would kill off everything and then the stink would return.

Yup!

 

[Comodave]

I would not use bleach as a cleaner.

 

[Xsbank]

Replace the hose with schedule 40 plastic pipe. It will never permeate. With my 2 - 1.5” pipe vents, my tank smells like a rose. Well, at least it smells “healthy.”

No bleach! Noflex Digester, one of the magic products that really works; a tablespoon down the head each day it’s being used, no sludge and no poop smell.

 

[flboy]

The odor is very bad in the cabinet that the hose runs through and you can smell it inside the boat a little bit too. I don't notice any odors outside the boat. I've also gotten a recent pump out and had no issues so I'd have to assume that the vent is working and allowing air in/out. I definitely feel like the vent line is what is stinking. There is about five or six feet of sanitation hose running up the side of the boat inside the cabinet that smells. The vent is installed about five feet up inside that cabinet. I've attached another pic that probably isn't very helpful but shows the vent hose running up the side of the boat inside the cabinet. The thru hull vent is just above the image. I can stop by the boat one day this week and take more pics if that helps.

 

[Bacchus]

If you are trying to confirm hose permeation you could loosen the fasteners and wrap it with plastic cling wrap to see if that stops the smell. If so you know the source if not need to keep exploring.

 

[HeadMistress]

There are two possibilities: Residual odor from the previous vent line or...You've replaced the vent line, but if you used the cheapest flex PVC hose, it can permeate very quickly...it did on my own boat in less than 90 days. Or, it could be a combination of residual odor and newly permeated hose.


There's a very simple test to determine whether the new vent line has permeated: Because residual odor can attach itself to the outside of the hose, clean a couple of feet of it using just detergent and water--NO BLEACH! Wet a clean rag in HOT water--as hot as you can handle. Wrap it around the clean section of hose. When the rag has cooled, remove it and smell it (you may have to go outside the boat to smell the rag to be sure). If you can smell anything on the rag, that hose has permeated. If you can't, it's still ok and means that the cabinet and everywhere else the old vent line has passed through is the culprit. Eliminating residual odor is a fairly easy job, albeit a bit labor intensive, using a product called PureAyre PureAyre which is available from a number of sources including Amazon.



[FONT=&quot]PureAyre is not an air freshener. .It's the only product I've found that eliminates ANY odor. Not only will it get of diesel and residual odor left behind by stinking sanitation hoses, but PureAyre is also rated for use around food...which means you can even use it to get rid of the odor left in your fridge by the steaks or fish that spoiled when a natural disaster took out shore power for 3 days. Also does a great job on musty PFDs and foulies.

How to use it:
You can never eliminate any odor unless you first eliminate the source...'cuz as long as the source continues to exist, it'll continue to generate new odor. So first you have to find and fix any leak or replace the stinky hoses, then--because PureAyre is NOT a cleaning product--thoroughly clean every surface, nook and cranny with detergent (Dawn is good) and water. Mop up an excess water and let the air dry till it's at least only damp...no standing puddles. Now you're ready to eliminate the residual odor. Use PureAyre full strength...I'd use pump garden spray jug set to a fine mist. Spray every surface, nook and cranny...just a light spray. Do NOT rinse...just let it dry with hatches open so that plenty of fresh air can circulate.
[/FONT]
[FONT=&quot]
[/FONT]
[FONT=&quot]If the soft goods in the cabin have picked up the odor, just spraying it on the surface won't do much...you need to spray enough on carpets and rugs to penetrate to the backing...enough to penetrate cushions to the middle from both sides..not enough to make 'em drippy, just enough to get into the cushion....you'll prob'ly have to remove the covers and send 'em to be cleaned. Again, just let everything dry. If you still have any odor, you missed a spot.

A spray bottle won't go very far...plus, it's cheaper in the long run to buy it by the gallon...it has an indefinite shelf life, so just keep it on hand. [/FONT]



--Peggie

 

[HeadMistress]

If you are trying to confirm hose permeation you could loosen the fasteners and wrap it with plastic cling wrap to see if that stops the smell. If so you know the source if not need to keep exploring.

There's only one brand of plastic wrap that'll work: Saran Wrap. Any others will permeate very quickly. You can't leave even a fraction of an inch of hose exposed, so you'll have to seal the ends with electrical tape.

I did this when I discovered that the flex pvc I'd used to rehose the system on my own boat had permeated in less than 90 days and decided to wait till the weather cooled off to rehose again. Saran did the job so well that I finally got around to it in the fall the following year.

That doesn't mean that Saran Wrap can be a permanent fix...it's just a band-aid you can use to buy time.

--Peggie

 

[FF]

On houses and RV it is common to vent thru the roof.


On boats it is more common to vent thru the hull above the heeled water line.


Any chance of using a 1 1/2 or 2 inch vent thru the hull?


The extra air will sweeten the tank, so no stink.


For problem RV they install an unpowered venturi roof fitting , to help suck more air out of the tank.

 

[Comodave]

There's only one brand of plastic wrap that'll work: Saran Wrap. Any others will permeate very quickly. You can't leave even a fraction of an inch of hose exposed, so you'll have to seal the ends with electrical tape.

I did this when I discovered that the flex pvc I'd used to rehose the system on my own boat had permeated in less than 90 days and decided to wait till the weather cooled off to rehose again. Saran did the job so well that I finally got around to it in the fall the following year.

That doesn't mean that Saran Wrap can be a permanent fix...it's just a band-aid you can use to buy time.

--Peggie

On a previous boat I was replacing all the waste system. There were not any guaranteed hoses that would not permeate at that time. So as a precaution I wrapped all the new hoses with Saran Wrap. Then I covered the Saran Wrap with clear packing tape. The hoses never smelled. A friend had a hose that had permeated in his aft cabin and he was too lazy to replace it so I told him about the Saran Wrap trick. He wrapped it and the smell was gone. It was still wrapped when he sold the boat and still no smell. It works.

 

[wkearney99]

On a previous boat I was replacing all the waste system. There were not any guaranteed hoses that would not permeate at that time. So as a precaution I wrapped all the new hoses with Saran Wrap. Then I covered the Saran Wrap with clear packing tape. The hoses never smelled. A friend had a hose that had permeated in his aft cabin and he was too lazy to replace it so I told him about the Saran Wrap trick. He wrapped it and the smell was gone. It was still wrapped when he sold the boat and still no smell. It works.

I have to think that just using better grade hoses would be a lots less hassle. Otherwise when the hoses do start to permeate you'll then be trapping waste in the plastic wrap, which is probably a pretty bad plan from a health perspective.

I get that wrapping a section as a band-aid may help. I just wouldn't look to do that as a long-term solution.

 

[wkearney99]

How is the hose routed from the tank? Because for a vent line you'd want to make sure it isn't set up such that it's allowing waste to slop up into the hose. We had a previous boat that has a terrible waste tank setup. The tank was along the centerline as was long and shallow. The vent line was at the aft end of the tank and that virtually guaranteed waste water was going to get dumped into the hose when the boat accelerated and ran up on plane. I eventually made it "less worse" by tapping a new vent line on the top and running the hose such that it had much more incline than before. This limited the amount of waste water that could get into the hose to about a 3' section, which was slanted to drain back into the tank when up on plane or at rest.

I'd double-check how your line is routed. Make sure there's NO dips anywhere along the path. Otherwise low spots will form a water trap and that will prevent the vent line from functioning properly (and thus lead to the tank stinking more than it should).

 

[rgano]

Replace the hose with schedule 40 plastic pipe. It will never permeate. With my 2 - 1.5” pipe vents, my tank smells like a rose. Well, at least it smells “healthy.”

No bleach! Noflex Digester, one of the magic products that really works; a tablespoon down the head each day it’s being used, no sludge and no poop smell.

PVC pipe will make a difference, just as Xsbank sez. And I would suggest finding out if there is another possible source by pumping and cleaning the tank until is is clean as a whistle and then filling it up from the pump out fitting and see if any leakage results. I fill emptied tank with soapy water until clear water comes out the vent on the side of the hull and run the macerator to empty it a few times and then blow down the vent. Looking around bilges before running the macerator tells me all is water tight.

 

[Comodave]

I have to think that just using better grade hoses would be a lots less hassle. Otherwise when the hoses do start to permeate you'll then be trapping waste in the plastic wrap, which is probably a pretty bad plan from a health perspective.

I get that wrapping a section as a band-aid may help. I just wouldn't look to do that as a long-term solution.

I was using the best grade hose that was available at that time. The Saran Wrap didn’t trap any waste inside it. When hose permeate it is the smell that comes through not the sewage.

 

[Nickair]

If the mentioned Saran Wrap test fails the smell stop. Based on what was disclosed here, you may simply have a unseen tank crack. Your comment of being strong when tank is close to full leads towards a possible tank crack. Free test for tank crack. Check the bottom or underneath of the cabinet, and bilge below and near the cabinet that smells. Also, open each floor locker/ storage/ bilge areas, one at a time, (after taking the boat out and using it.) Smell in these areas will identify a tank crack. Tanks are not expensive. Hopes are it is the vent hose and residual smell.