Holding tank vent hose

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SILENTKNIGHT

SILENTKNIGHT

Senior Member
Joined
Oct 19, 2018
Messages
191
Location
United States
Vessel Name
STELLA DI MARE
Vessel Make
2006 MAINSHIP 34T
2006 Mainship 34T. It appears to difficult to run a new vent hose, no up to it. I do have a smell after flushing and all the folk on the dock complain.:rolleyes:.. When i nspected the vent line hose ( see photo) i noticed there appears to be a kinked portion at the bend as it goes through the opening . There is no wiggleroom alongside the pump out hose to straighten it out . My solution it to splice into it at the kink a 5/8 barb and route it over the top of thePVC hole or use the hole opening next to it. This would then give me access to back flush when needed. I cant back flush from the starboard side because its not a mushroom vent. But i believe the kink is preventing airflow( its pinched). I just emptied the tank , and i opened the sending unit and used a garden hose to blast the walls and bottom of the tank.
 

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Greetings,
Mr. S. MY vote would be to use the other opening. If at ALL possible, I would avoid cutting and adding a barbed fitting. The constriction in the fitting may be equal to the kink constriction. Solid, continuous hose.
 
Probably have to reroute and use a new hose Route through the other opening so you only have to do it once. I too would want to avoid a fitting especially as the vent hose already looks on the small side. It is often easy to use the original hose to pull another new one back through.
 
That vent hose is simply too small to do any good as far as the smell issue. It may pass a bit of air into the tank while pumping out and thus prevent the tank from collapsing but as far as getting air, oxygen, into the tank it is useless. My advice would be to install a bubbler system to help the tank become aerobic. Then the smell will be gone. The easy route would be to buy a Groco Sweetank system. A lot of people here have made their own system and it is cheaper. By pumping air continuously into the tank your tank will be aerobic not anerobic, so it will not smell when you flush the head. The other solution is to add 2 large vents, 1 to each side of the boat. I did 2 1.5” vents and I have no smell.
 
My only option on this boat was to add an odor filter to the 5/8-inch hose and to make it easily accessible with threaded end fittings for easy change out. The hard part was the boat yoga required to cut the zip ties holding the vent hose in place WAY over in a corner and pull it to the point where I could cut it to insert the barbs of the two filter end caps. The end result is the filter clipped to the underside of the cockpit deck several inches above the top of the tank with an ascending line up the the mushroom vent.
 

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rgano said:
My only option on this boat was to add an odor filter to the 5/8-inch hose and to make it easily accessible with threaded end fittings for easy change out. The hard part was the boat yoga required to cut the zip ties holding the vent hose in place WAY over in a corner and pull it to the point where I could cut it to insert the barbs of the two filter end caps. The end result is the filter clipped to the underside of the cockpit deck several inches above the top of the tank with an ascending line up the the mushroom vent.
Click to expand...
This project is on my "Boat Yoga" winter project list! Not one I'm looking forward to,but as always I gain guidance from the Yoga Guru, Rich Gano! :)
 
I wish you plenty of good sleep that night via ibuprophen, Bill, cuz this type of yoga will stretch all the muscles you didn't know you had.😒
 
I'm not intimately familiar with the MS Pilot tank & hose arrangement but I was able to run a new vent line from my tank fitting to the bow area. The bow already had an AC cooling water discharge as well as anchor licker drain and was accessible by removing the bed headboard. The benefit was access and a rather straight run from front of the tank.
My Bacchus website -Projects outlines the bubbler system I built & installed for roughly $50. It's been in use for 11 seasons running 24/7 and made a huge improvement in smell. IMO adding a bubbler is the easiest & most efficient way to counter holding tank smells.
I would work long & hard to avoid adding a vent filter... solve the problem vs just hiding it.
 
Thank you all for your reply. I will start my yoga class and put a larger hose and mushroom thru hull. I also bought Zall digester to use in tank. i noticed alot of places discontinued the product.
 
Bacchus said:
I'm not intimately familiar with the MS Pilot tank & hose arrangement but I was able to run a new vent line from my tank fitting to the bow area. The bow already had an AC cooling water discharge as well as anchor licker drain and was accessible by removing the bed headboard. The benefit was access and a rather straight run from front of the tank.
My Bacchus website -Projects outlines the bubbler system I built & installed for roughly $50. It's been in use for 11 seasons running 24/7 and made a huge improvement in smell. IMO adding a bubbler is the easiest & most efficient way to counter holding tank smells.
I would work long & hard to avoid adding a vent filter... solve the problem vs just hiding it.
Click to expand...
Don, the use case as well as the boat design here had a lot to do with the decision to filter instead of cross ventilate or install a bubbler. My boat is a day boat in general use with light to no use of the head, although we ONCE spent six days aboard during a local area cruise. The vent is a preventive measure in the event we ever elect to spend a night or more aboard again. Any use of the waste tank in day trips is cleaned out rather quickly with the tank remaining as in new condition on a routine basis. One of our "Piloteer group" members is planning to install a bubbler system soon, and we will follow that closely. Running even a wire from place to place in a 30 P is an exercise in extreme boat yoga and usually some drilling, filling, and cursing. Running a hose and installing a vent of sufficient size (see Dave's post) to cross ventilate our 17-gallon waste tank would involve cutting and gaining access in ways highly destructive and externally ugly on this small boat I'd rather not think about, and in our particular case just plain overkill. It's just a case of different strokes for different folks.
 
rgano said:
Don, the use case as well as the boat design here had a lot to do with the decision to filter instead of cross ventilate or install a bubbler. My boat is a day boat in general use with light to no use of the head, although we ONCE spent six days aboard during a local area cruise. The vent is a preventive measure in the event we ever elect to spend a night or more aboard again. Any use of the waste tank in day trips is cleaned out rather quickly with the tank remaining as in new condition on a routine basis. One of our "Piloteer group" members is planning to install a bubbler system soon, and we will follow that closely. Running even a wire from place to place in a 30 P is an exercise in extreme boat yoga and usually some drilling, filling, and cursing. Running a hose and installing a vent of sufficient size (see Dave's post) to cross ventilate our 17-gallon waste tank would involve cutting and gaining access in ways highly destructive and externally ugly on this small boat I'd rather not think about, and in our particular case just plain overkill. It's just a case of different strokes for different folks.
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Rich
I agree with the difficulty running additional / larger vent lines and was what prompted me to attempt the bubbler route. Even on my MS 34HT with an access plate in the area of my fuel fill, holding tank pump out and multi vent fittings it was impossible to change out the factory tank vent fitting to a mushroom fitting. Ultimately, (after bubbler install) it was more expediant to abandon the old and run new vent. That was really a belt & suspenders back up in case my bubbler pump failed.

I have a hard time imagining a situation where finding a way to get 1/2A @ 12V to an area where a bubbler pump could be installed... even if one had to piggy back onto an existing circuit. The pump draws less than 1/2A. I actually mounted it on the opposite side of a bulkhead to reduce the sound in my fwd cabin and simply ran the ~1/8" tubing to the tank by pushing it through a caulked hole in the bulkhead.

It only after a few seasons of looking for alternatives for vent replacement that I came up with the idea to run under the fwd cabin to the bow area. The beauty of ventbat the bow is it is generally more open to breezes vs sides of the hull blocked by docks. The bow is also far away from interior & exterior
I get it that each boat is unique and what's easiest or even possible on one can be difficult/ impossible on others. I offer alternatives for others to consider but don't mean them as best or even doable alternatives for everyone.

occupancy locations that even a smelly vent goes virtually unnoticed.
 
I am wading in this pool on my boat and after several pages of discussion, even a larger vent line is unlikely to contribute to odor control. The holding tank vent line has two missions. First, to allow gasses out when new contents enter the tank and air in when contents are pumped out. And second, to allow oxygen to enter the tank passively to help prevent anaerobic conditions from developing in the tank. It is that second mission that impacts odor control.

Even with all the right diameters, lengths, and slopes, using a single vent line to prevent a tank full of really foul smelling liquid from stinking is very optimistic. Most are recommending at least two vent lines to allow cross ventilation, or even better an air pump to bubble air into the tank. No matter how many vent lines I add, the location of my holding tank precludes having the right lengths and slopes of those lines. I may someday elect to install a bubbler, but for now I'm staying with the periodic sodium percarbonate dosing.

I am upgrading the vent line to 1" hose with a proper through hull fitting, but that will only allow the gas out and air in mission. Good luck!
 
If you can’t do 2 good size vents then just do one as big as you can and then add a bubbler system. Problem fixed.
 
Comodave said:
If you can’t do 2 good size vents then just do one as big as you can and then add a bubbler system. Problem fixed.
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My experience was adding the bubbler, even with the old inadequate vent, solved the smell problem. It was several seasons later that I found a way to run a new vent (at the bow) and use a mushroom thru hull.
Note: the old functioned enough to avoid any pressure / vacuum build- up.
 
Of all the boats out there with holding tanks, what fraction have bubbler systems? I bet it's a small fraction. Perhaps not among Trawler Forum members, but among the general cruisers and weekend boaters population. Point is, the overwhelming majority of holding tank "contents" do not smell good. The stink that is made public for neighbors to object is only made public for the minute or so following a significant flush event. Most of the time that stink is held in the holding tank.
 
We had a boat that had an 80 gallon holding tank that when you flushed a head would knock people over on the dock. It was so bad that my wife would try not to use the head when anyone was around. That was the first time I spoke to Peggie. She listened to me about the problem. Then suggested a Groco Sweetank. I put one in and we stayed late on it Sunday when everyone had gone home and we turned it on. OMG the stink was tremendous. But as Peggie said give it 2 hours and the smell was gone.
 
HeadedToTexas said:
Of all the boats out there with holding tanks, what fraction have bubbler systems? I bet it's a small fraction. Perhaps not among Trawler Forum members, but among the general cruisers and weekend boaters population. Point is, the overwhelming majority of holding tank "contents" do not smell good. The stink that is made public for neighbors to object is only made public for the minute or so following a significant flush event. Most of the time that stink is held in the holding tank.
Click to expand...
The better question is how many have a holding tank smell they wish they didnt?
Boat mfgrs don't care if they provide sweet or stinky smells...,they only report holding tank capacity and let owners deal with neighbors and smell
 
Ensure that the back flow valve at the base of the toilet is functioning. I went through adding a second larger oppsite vent line with inadequate results only to notice bubbling after flushing a bowl full of water. This indicated fluid from the siphon loop returning to the bowl due to the failing joker valve. Solved my problem.
 
Bacchus said:
I'm not intimately familiar with the MS Pilot tank & hose arrangement but I was able to run a new vent line from my tank fitting to the bow area. The bow already had an AC cooling water discharge as well as anchor licker drain and was accessible by removing the bed headboard. The benefit was access and a rather straight run from front of the tank.
My Bacchus website -Projects outlines the bubbler system I built & installed for roughly $50. It's been in use for 11 seasons running 24/7 and made a huge improvement in smell. IMO adding a bubbler is the easiest & most efficient way to counter holding tank smells.
I would work long & hard to avoid adding a vent filter... solve the problem vs just hiding it.
Click to expand...
Hi Don,
I'd be interested is knowing more about the bubbler system you built. photos, link to site, details?
 
BCK said:
Hi Don,
I'd be interested is knowing more about the bubbler system you built. photos, link to site, details?
Click to expand...
Brian
Take a look at my linked Bacchus website... Projects section. I've tried to document the major & some minor projects I've completed on Bacchus. The only mod I've made to my original bubbler is the rlacement of the metal distribution tube with PVC. Amazingly, the bubbler is still operating 24/7 for 11 seasons in the NE. I'm still using NoFlex treatment and plan to continue with generic Sodium Percarbonate when my supply runs out.

Happy to answer any questions.
 
Bacchus said:
Brian
Take a look at my linked Bacchus website... Projects section. I've tried to document the major & some minor projects I've completed on Bacchus. The only mod I've made to my original bubbler is the rlacement of the metal distribution tube with PVC. Amazingly, the bubbler is still operating 24/7 for 11 seasons in the NE. I'm still using NoFlex treatment and plan to continue with generic Sodium Percarbonate when my supply runs out.

Happy to answer any questions.
Click to expand...
I cannot find the projects section or your website
 
Boy, I thought my engine bay was tight in some areas. Now that's tight. Makes me feel like I could play basketball in my engine bay in comparison.
 
HeadedToTexas said:
That is impressive, Don. Why the percarbonate if the bubbler is supplying oxygen to the holding tank contents?
Click to expand...
It works and unfortunately I implemented both at the same time. Little interest in experimenting to quantify affect of each. SPC seems to do a good job of breaking down waste and helping keep tanks cleaner. I'm happy with belt & suspenders. I have a supply of NoFlex on hand and the $ of generic SPC is small enough that I'll likely continue when I run out of NoFlex.
 
The sodium perconate can’t hurt. I put some in my holding tank occasionally.
 
I tried treating my tanks with sodium percarbonate regularly this year. Very noticeable improvement in the smell going out the vent when flushing. I buy it in bulk from Amazon.
 
Bacchus said:
It works and unfortunately I implemented both at the same time. Little interest in experimenting to quantify affect of each. SPC seems to do a good job of breaking down waste and helping keep tanks cleaner. I'm happy with belt & suspenders. I have a supply of NoFlex on hand and the $ of generic SPC is small enough that I'll likely continue when I run out of NoFlex.
Click to expand...
i used NOFLEX ! recently due to vent hose odors..... its amazing how fast it dissoolves evreything. Follow instructions. Best results let sit for a week, the entire tank is clear. no smell
 
For those using sodium percarbonate, are you using it alone? I switched from Happy Campers to Noflex in 2023, and while Happy Campers was good, Noflex is better. It seems that sodium percarbonate might be just as good and a lot more economical.
 
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