Waste Tank Vent Hose Smell

flboy · 01-17-2020, 10:45 AM

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

Soo-Valley · 01-17-2020, 11:00 AM

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 · 01-17-2020, 11:11 AM

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 · 01-17-2020, 11:23 AM

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** · 01-17-2020, 11:28 AM

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 · 01-17-2020, 11:42 AM

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 · 01-17-2020, 11:44 AM

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 · 01-17-2020, 11:46 AM

Quote:

Originally Posted by 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.

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.

Soo-Valley · 01-17-2020, 12:53 PM

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** · 01-17-2020, 12:59 PM

Quote:

Originally Posted by flboy

...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 · 01-17-2020, 01:03 PM

Quote:

Originally Posted by 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.

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** · 01-17-2020, 08:28 PM

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 · 01-17-2020, 08:36 PM

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

Comodave · 01-17-2020, 08:37 PM

Quote:

Originally Posted by Soo-Valley

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 · 01-17-2020, 10:44 PM

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 · 01-18-2020, 11:12 AM

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 · 01-18-2020, 11:23 AM

Quote:

Originally Posted by 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.

Yup!

Comodave · 01-18-2020, 01:58 PM

I would not use bleach as a cleaner.

Xsbank · 01-18-2020, 05:14 PM

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 · 01-20-2020, 10:34 AM

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.