Holding tank filter

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All bay long

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Mar 31, 2022
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Sorry gang if this has been posted before. I have a 1997 36’ Sabre express that has a sack type holding tank. It was never equipped with a carbon filter. I want to install one but would like to know if there is a particular distance from the holding tank that I should install it.
 
I don’t know if I would trust a bladder holding tank. I would be worried about it leaking. Generally holding tank vent filters are a bad thing. They inhibit air flow through the tank. Air flow is what stops the smells in a holding tank. Without air flow, actually oxygen, you get anerobic bacteria growing and that is what really stinks. Aerobic bacteria doesn’t stink, because it has oxygen. I always put in 2 large vents in my holding tank and don’t need any filters or chemicals. But I don’t know how to do that with a bladder holding tank. If it were my boat I would toss the bladder tank and get a quality plastic tank from Ronko.
 
Don't add a filter. Add a chemical such as Sodium Percarbonate each time you flush and periodically clean the tank. Adding a filter limits the flow of air in and out that inhibits the natural breakdown process (which removes the odor from your waste tank).

Holding Tank Cleaning, the Easy Way

If your holding tank looks like the upper part of this one and you want it to look like this one I have the answer. So, my holding tank was so fouled on the inside, that I couldn't see the liquid level. What started out as a process to just be able to see the level became an obsession to...
www.trawlerforum.com www.trawlerforum.com

Ted
 
LOL made me think of these "sack type" tanks:

Glenmal 5 Gallon Bucket Portable Camping Toilet Seat Toilet Bags Camping Hiking https://a.co/d/0jg21bbh

But seriously, to the OP question, assuming it has a standard vent line and vacuum head (etc) then I expect the standard installation for a Big Orange filter or the like would be fine.
 
Thank you all for your replies. This bladder type holding tank is about 10 years old and still doing great! It does well with the layout as you can get these type of tanks into oddball places without any major dismantling of surrounding materials. I guess based off alot of the responses that it’s a bad idea to put any type of restriction inline of the vent hose so, I’ll leave well enough alone and just deal with the odor when we flush. 🤮
 
All bay long said:
I’ll leave well enough alone and just deal with the odor when we flush.
Click to expand...

You should be able to eliminate tank odor. Note ted's comment about Sodium Percarbonate. Or NoFlex Digestor is a pre-made product designed to promote aerobic bacteria in holding tanks. Available from places like marinesan.com, Fisheries Supply, etc. and less expensive if you buy 6 or more at a time.

-Chris
 
I agree with recommendation of Ted, Dave & others against filters. Use NoFlex or generic sodium percarbonate if desired... it does help significantly.
 
I removed our filter when I replaced all sanitation hoses, freshwater lines, new ME toilet, all fixtures, new sump, added water tank, etc. No odors and everything new.
 
Last edited:
PhilPB said:
...when I replaced all sanitation hoses...
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That's a good point. Are you sure it's the vent that stinks and not the hoses themselves? While the material seems impermeable, it is permeable and the stink permeates over time. Rub a damp rag on the some of the hoses. The damp rag should smell damp, but not stink like sewer gas.

And buy a copy of The Head Mistress' book. You will be glad you did.
 
Mud Runner - i bought a 1.87 L container of charcoal, filled the pipe full and i doubt i used half of the container. so i have plenty left to change it out next season if necessary.

as to the charcoal getting wet. this is the type used in fish aqauriums so it 't get all gummy when wet. still a good idea not to get it wet.

hadn't thought about installing a second vent, but i am sure it wouldn't be that hard to do.
 
We all know that getting more air in contact with the sewage will encourage aerobic bacteria and reduce bad odor. The problem I see with a bladder tank is that the top of the tank is always in contact with the sewage. This blocks just about all air/sewage contact. Adding another vent isn’t going to increase sewage/air contact.
 
That is why I would replace it with a quality plastic tank.
 
+1 to Noflex, it works great. Shop around though as prices vary wildly in my experience. Generic percarbonate is another another possibility as noted.

I assume the Sabre has fresh water flush, but just in case, if it's raw water flush, I would change that to fresh water before or along with any of the other recommendations here (agreed on the plastic tank, anything flexible makes me nervous!)
 
ACT09 said:
Mud Runner - i bought a 1.87 L container of charcoal, filled the pipe full and i doubt i used half of the container. so i have plenty left to change it out next season if necessary.

as to the charcoal getting wet. this is the type used in fish aqauriums so it 't get all gummy when wet. still a good idea not to get it wet.

hadn't thought about installing a second vent, but i am sure it wouldn't be that hard to do.
Click to expand...
It may not be necessary if you replace the "vent" thru-hull, which is designed to keep sea water out of the fuel and water tanks so doesn't allow any air exchange, with an open bulkhead (aka "mushroom") fitting. This will allow the air exchange needed to keep the tank aerobic and has the added advantage of allowing you to prevent vent blockages by putting a hose nozzle against it to back flush the vent line every time you pump out and/or wash the boat. Anything that's tried to set up housekeeping in it will just get a water slide ride into the tank.

--Peggie
 
sjisailor said:
LOL made me think of these "sack type" tanks:

Glenmal 5 Gallon Bucket Portable Camping Toilet Seat Toilet Bags Camping Hiking Amazon.com

But seriously, to the OP question, assuming it has a standard vent line and vacuum head (etc) then I expect the standard installation for a Big Orange filter or the like would be fine.
Click to expand...
I endorse the Big Orange filter, no restrictions and it works
 
...hadn't thought about installing a second vent, but i am sure it wouldn't be that hard to do.

I wish I could have invented a product that actually helps to create the very problem it’s sold to solve, because that’s what a vent line filter does. Filters do trap the gasses which try to escape through the vent line, but they impede the free exchange of air needed to prevent odor from forming in the first place, eliminating the need for a filter! What’s more, they only last about a year, are toast immediately if they get wet--which makes it impossible to backflush the vent line to prevent blockages

Oxygen is the key to odor prevention, so instead of a second vent or a filter, install an aerator. Many boat owners have created aerators using a fish tank or live well aerator and perforated hose...another reason I strongly recommend replacing the "vent" thru-hull with an open bulkhead fitting, 'cuz They do need to run 24/7 except during winter or other extended layup, 'cuz the tank will turn anaerobic--and stinky--without the input of any fresh air 'cuz "vent" thru-hulls are almost as bad as filters when it comes letting air out of the vent. But fresh air doesn't cost anything and you'll still be able to back flush the vent line regularly to prevent blockages and you may not even need to use any tank product.

--Peggie.
 
HeadMistress said:
...hadn't thought about installing a second vent, but i am sure it wouldn't be that hard to do.

I wish I could have invented a product that actually helps to create the very problem it’s sold to solve, because that’s what a vent line filter does. Filters do trap the gasses which try to escape through the vent line, but they impede the free exchange of air needed to prevent odor from forming in the first place, eliminating the need for a filter! What’s more, they only last about a year, are toast immediately if they get wet--which makes it impossible to backflush the vent line to prevent blockages

Oxygen is the key to odor prevention, so instead of a second vent or a filter, install an aerator. Many boat owners have created aerators using a fish tank or live well aerator and perforated hose...another reason I strongly recommend replacing the "vent" thru-hull with an open bulkhead fitting, 'cuz They do need to run 24/7 except during winter or other extended layup, 'cuz the tank will turn anaerobic--and stinky--without the input of any fresh air 'cuz "vent" thru-hulls are almost as bad as filters when it comes letting air out of the vent. But fresh air doesn't cost anything and you'll still be able to back flush the vent line regularly to prevent blockages and you may not even need to use any tank product.

--Peggie.
Click to expand...
AMen Peggie... your guidance has been instrumental to me solving odor problems on our current & previous boats. Prior was successful w a 2nd larger / straighter vent. Current boat I linstalled a $30 fish tank bubbler that is still going strong after 10+ seasons. IMO Bubbling is the sure fired solution to solving tanks odor problems... highly recommend it for anyone w odors issues.
 
My problem disappeared as soon as I removed the vent filter on our holding tank. Been odor-free ever since. Thanks Peggie!
 
You folks r all just filter deniers!! They work great (at least mine does).

My experience with bladder tanks is that they stink unless there is new technology in the last few years.
 
That they cannot be managed aerobically to PREVENT odor from being generated Is one of the reasons why bladder tanks aren't recommended for sewage holding...odor can only occur in ANaerobic conditions.

----Peggie
 
Question for Peggie or anyone else with experience…
Situation: I’ve got a 5/8” vent hose leading to a 50 gal holding tank. I replaced the almost blocked thru hull vent with a mushroom vent. I regularly back flush the vent when pumping out. It definitely works better. Access to our tank is limited. We have been using only Noflex for 8-9 years. 2 Vaccuflush toilets. All hoses new. Still stinks from the vent when flushing and we are over about 1/2 full. Doesn’t stink anywhere else.

Question: I would like to install an aerator/fish bubbler. Could I just put that bubbler air into the top of the tank and forgo trying to get it down into the liquid? In other words, the air would just get introduced into the tank just like having another vent. It would be a much simpler install and avoid possible plugging issues.
 
You could certainly try it. Using a submerged bubbler system would probably work better but if it doesn’t work without the bubbler then go back and install the bubbler. I use 2 large vents so the air is just moving across the top of the sewage and it seems to work ok.
 
Greetings,
Mr. w. I think simply immersing an air tube without the bubbler/disperser would work with less danger of clogging. The end goal is to aerate the liquid (supply oxygen) and encourage aerobic bacteria to grow.
 
I used the Uniseal to add the 2 vents to my tank. I just left the stock 5/8” vent in place . The stock vent did have a filter in it. But since I added 2 1.5” vents I just left it alone.
 
Here's another testimonial to Peggy's recommendation to make sure your vents are clear, your vent lines are large enough and clear, and don't use a vent line filter. I was very skeptical about Peggy's advice, heck, how could all those boat designers be wrong? They all use filters, marine supply stores sell piles of them, my system was designed to use one - but once I removed the filter, the persistent holding tank smell problem vanished and never came back.
 
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