I could do that I think. It would be easier if I understood what you mean by "open bulkhead thru hull"
Holding Tank Vent Filter
- Thread starter med2463
- Start date
- Status
Oh. OK. That's what is on the vent now. Have a clam shell over a similar fitting for the fuel vent. Never heard the term "open bulkhead thru hull" before yesterday.
What do you think about runing the vent into the anchor locker instead of out thru the hull side?
What do you think about runing the vent into the anchor locker instead of out thru the hull side?
Last edited:
One more shot...The problem with odor coming out of the fvent line is because not enough air is getting into the holding tank to break down the waste. Even Peggy will agree to that.
The reason not enough air is getting into the tank is because of:
1. Clogged vent line.
2. An extremely long vent line that is required because of the location of the holding
tank.
Vent filters are porous. The activated carbon crystals dont form a solid block: They allow escaping gasses to pass thru the crystals and absorb the odors. Pressure does not build up in the line or holding tank.
If the activated carbon gets saturated-by overfilling the holding tank or by the vessels excessive healing, they must be replaced. That is a simple process-disconnect the filter from the vent line, pour out the old carbon and replace with new carbon. It would take about 5 minutes and costs about $2.
This is far less expensive that contimually adding expensive chemicals that dont do the job. Bob
The reason not enough air is getting into the tank is because of:
1. Clogged vent line.
2. An extremely long vent line that is required because of the location of the holding
tank.
Vent filters are porous. The activated carbon crystals dont form a solid block: They allow escaping gasses to pass thru the crystals and absorb the odors. Pressure does not build up in the line or holding tank.
If the activated carbon gets saturated-by overfilling the holding tank or by the vessels excessive healing, they must be replaced. That is a simple process-disconnect the filter from the vent line, pour out the old carbon and replace with new carbon. It would take about 5 minutes and costs about $2.
This is far less expensive that contimually adding expensive chemicals that dont do the job. Bob
That depends on whether you do the anchoring or whether you have crew to do the anchoring for you. Another decision factor may be whether you ever want them to do the anchoring again.
Imagine opening up that lid on a hot day!
The vent line only stinks for a minute when someone flushes. The anchor locker already stinks, and will till hurricane season when I install a washdown as a part of redoing the entire bow/anchor/anchor locker.
I always anchor, the admiral drives. Although we had friends who selected their primary anchor based on how much Mrs friend was comfortable lifting.
I always anchor, the admiral drives. Although we had friends who selected their primary anchor based on how much Mrs friend was comfortable lifting.
The gas that emits from the vent line is caused from insufficient oxygen in the holding tank. This is because of:
A clogged vent line.
An extremely long vent line that is required because of the location of the holding tank.
No amount of chemical is going to mask the problem of a long vent line. When runs are horizontal, they negate the venting process.
The easiest, cheapest, most effective solution is a filter on the vent line. The filter element of activated carbon absorbs the noxious gasses. The crystals are not packed firmly enough to create back pressure. They allow for pressure to escape, just as they allow gas to escape.
If (because of over flow or healing) the crystals become "Tainted", its a simple matter to disconnect the filter, empty out the carbon and refill with more activated carbon and reinstall. Cost to refill, about $2.
A clogged vent line.
An extremely long vent line that is required because of the location of the holding tank.
No amount of chemical is going to mask the problem of a long vent line. When runs are horizontal, they negate the venting process.
The easiest, cheapest, most effective solution is a filter on the vent line. The filter element of activated carbon absorbs the noxious gasses. The crystals are not packed firmly enough to create back pressure. They allow for pressure to escape, just as they allow gas to escape.
If (because of over flow or healing) the crystals become "Tainted", its a simple matter to disconnect the filter, empty out the carbon and refill with more activated carbon and reinstall. Cost to refill, about $2.
Bill:
The first thing I would try is to just replace the current thru hull and be sure that you back flush it every time you pump out.
I would also try Odorlos if you are not using it. The original holding tank on the H37C was under the shower seat, so the vent line is not very long. I actually use two different chemicals in my head (Unique Marine Treatment and Odorlos) and have not had much of an issue. When the tank is near capacity we will get some odor in the cockpit, but our tank is in the stern area.
If you run a vent line all the way up to the anchor locker it would probably just make matters worse.
http://uniquemm.com/mdiinstructions.html
This stuff is realitively inexpensive $10-12 and you only use a couple of cap fulls at a time. The reason I use this is the fact that is supposed to clean out any TP & sludge that may be building up.
The first thing I would try is to just replace the current thru hull and be sure that you back flush it every time you pump out.
I would also try Odorlos if you are not using it. The original holding tank on the H37C was under the shower seat, so the vent line is not very long. I actually use two different chemicals in my head (Unique Marine Treatment and Odorlos) and have not had much of an issue. When the tank is near capacity we will get some odor in the cockpit, but our tank is in the stern area.
If you run a vent line all the way up to the anchor locker it would probably just make matters worse.
http://uniquemm.com/mdiinstructions.html
This stuff is realitively inexpensive $10-12 and you only use a couple of cap fulls at a time. The reason I use this is the fact that is supposed to clean out any TP & sludge that may be building up.
"you can install a Groco Sweetank system Groco Sweetank installation instructions (aeration system. When installed, operated and maintained according to directions, it completely eliminates holding tank odor out the vent without the use of ANY tank product, paying for itself in only few seasons."
Peggy on the Groco unit;
Does the control unit have a programmable timer feature? This would be necessary on a mooring, don't want it running continuously, loading the batteries, and when sitting for a couple of weeks one would want to have it run sometime.
Without having a backing nut on the through tank bulkhead, does this concern you especially when a side installation is the only option? I'm not sure I understand how effective the seal is over the long haul.
Peggy on the Groco unit;
Does the control unit have a programmable timer feature? This would be necessary on a mooring, don't want it running continuously, loading the batteries, and when sitting for a couple of weeks one would want to have it run sometime.
Without having a backing nut on the through tank bulkhead, does this concern you especially when a side installation is the only option? I'm not sure I understand how effective the seal is over the long haul.
No...it has to run 24/7/365 (except during winter layup, of course) unless you want odor. However it only consumes 3 watts on 12v (not sure what that translates too in AH), which can easily be supplied by a solar panel.
It's been on the market nearly 10 years now...I've never heard of a single seal failure or leak.
All this said, I only mentioned the Sweetank to compare the cost of a permanent odor cure with with filters...but it's rarely if ever necessary to resort to aerating a tank much smaller than 40-50 gallons...and there aren't very many tanks that size on the sailboats here. Passive ventilation will work at least 95% of that are smaller than that. It can sometimes be a bit more effort to do the system mods necessary to make passive ventilation work, but worth it in the end because you end up with an odor free system that doesn't need filters or consume any power.
If the tank is in the bow, it's what I'd recommend...and you DO mean to a thru-hull in the anchor locker, not a vent ending the anchor locker?
However, if the tank location would make the vent line longer than 5', it won't work.
That much is true... The answer is obvious: shorten the vent line, which may require a new vent thru-hull....which is a lot less expensive than a filter.
No...it's VERTICAL vent lines that prevent the exchange of air with gasses. Gasses, even odorless CO2, in the tank are heavier than air...they don't rise. Fresh air, especially warm air, doesn't fall. Not much can happen if the vent line isn't straight either, 'cuz only air/gasses under pressure can travel around corners...and air/gasses in a holding tank are only under pressure when incoming waste pushes air out the vent.
So (for the umpteenth time) the vent line should be straight, <5', (ideally no more than 3') and have a maximum vertical rise of 45 degrees.
Y'all might consider reading my book...see link in my signature.
Peggy,
"So (for the umpteenth time) the vent line should be straight, <5', (ideally no more than 3') and have a maximum vertical rise of 45 degrees."
This may be impractical for many boat layouts, including mine.
As far as the power consumption, on my solar system (~60w max) over the course of a sunny day and the air pump drawing ~230 mils for 24/7 (using an average of 13v) would consume roughly about 1/3 of my charging capacity for the best case. Doable, but not sure I want to setup a possible trap if my charging system were to fail for some reason. Another approach that might help mitigate the risks would to qualify the air pump activation with a voltage sensing circuit so that when the solar system charging it would sense the rise in voltage and kick the pump on. These are in-line devices that are readable available and used for portable coolers that plug into cigarette lighters to keep from running down your car battery.
It's hard for me to believe that the system must run all the time to provide some effectiveness. I would think at some point more air would not provide anymore action if the tank has not had new effluent induced.
Further...
"All this said, I only mentioned the Sweetank to compare the cost of a permanent odor cure with with filters...but it's rarely if ever necessary to resort to aerating a tank much smaller than 40-50 gallons...and there aren't very many tanks that size on the sailboats here."
From this statement I should deduce that for my meager tank this system would not be necessary, so I'm wondering how practically I'm going to get better aerobic action?
"So (for the umpteenth time) the vent line should be straight, <5', (ideally no more than 3') and have a maximum vertical rise of 45 degrees."
This may be impractical for many boat layouts, including mine.
As far as the power consumption, on my solar system (~60w max) over the course of a sunny day and the air pump drawing ~230 mils for 24/7 (using an average of 13v) would consume roughly about 1/3 of my charging capacity for the best case. Doable, but not sure I want to setup a possible trap if my charging system were to fail for some reason. Another approach that might help mitigate the risks would to qualify the air pump activation with a voltage sensing circuit so that when the solar system charging it would sense the rise in voltage and kick the pump on. These are in-line devices that are readable available and used for portable coolers that plug into cigarette lighters to keep from running down your car battery.
It's hard for me to believe that the system must run all the time to provide some effectiveness. I would think at some point more air would not provide anymore action if the tank has not had new effluent induced.
Further...
"All this said, I only mentioned the Sweetank to compare the cost of a permanent odor cure with with filters...but it's rarely if ever necessary to resort to aerating a tank much smaller than 40-50 gallons...and there aren't very many tanks that size on the sailboats here."
From this statement I should deduce that for my meager tank this system would not be necessary, so I'm wondering how practically I'm going to get better aerobic action?
Easier on most than you think...email me, we'll discuss how to do it on your boat.
Aeration doesn't kill "bad" bacteria...in fact, the whole concept of "good" and "bad" bacteria is actually a myth...it's only whether the environment they're in is aerobic or anaerobic that matters. When bacteria can function aerobically, they produce CO2, which is odorless. But when they function ANaerobically, they produce hydrogen sulflde and sulfur dioxide, which stink and are toxic, along with methane which is odorless, but toxic and also flammable. While the tank contents are being aerated conditions remain aerobic...so the gasses they produce are odorless. But when aeration is discontinued, conditions in the tank become anaerobic resulting in stinky gasses.
However, you're right that EVENTUALLY nothing more would happen until new effluent is added...but only after the bacteria in the tank have completed exhausted their food source (waste) and died...that can take a month or longer in just a few gallons of waste. A tank that's turned anaerobic CAN be recovered, but that takes days during which aeration can only force the anaerobic gasses already in the tank out the vent...which start out VERY ripe and gradually diminish as the aerator replaces all those gasses with oxygen. You wouldn't want to be downwind of the tank vent the first day or two of aeration after the boat has sat in the summer heat with it off for a week!
And now I think you understand why an aeration system needs to run 24/7/365 to keep the tank odor free. And yes, you can deduce that it shouldn't be necessary for your "meager" tank. Email me...I'll be glad to help you figure out what your particular installation needs to increase the ventilation.
I'd do it while the weather is cool...things get a LOT stinkier in hot weather! Installing a new vent thru-hull is a two hour job at most. We need to talk about where to put it, though.
K.O. and Odorlos...Combine or not...up to you. Odorlos is one of the few products that can be combined with K.O. without killing the bacteria. However, I would start out by thoroughly flushing out the tank...which should be done 2-3x/season (3-5x year in FL and other latitudes that allow year round boating) anyway...to flush out any sludge. I've posted instructions for doing that the right way--which is much easier than the way most people try to do it--in the HM forum several times.
Thanks but we boat when the weather is cool, work on the boat in the hot and humid. I put an A/C on the boat mostly for summer chores. With guidance from your book, I put all my fittings on top, so changing the vent hose is just removing an easily acessible hose clamp. We pump out on the way home from cruising, but with a taper on the pick-up tubes, we can't empty the tank completely even when we pump overboard.
We have LOTS of electricity on board, but I have other places to spend $317, so no aerator just yet.
Anyway, it's just a whiff when someone flushes. Makes me sure the vent is open, not plugged. No odor at all other times, not gonna give up cruising in the good weather just for an ocasional whiff.
We have LOTS of electricity on board, but I have other places to spend $317, so no aerator just yet.
Anyway, it's just a whiff when someone flushes. Makes me sure the vent is open, not plugged. No odor at all other times, not gonna give up cruising in the good weather just for an ocasional whiff.
- Status