Recommissioning head and holding tank

Sep 24, 2018
3,437
Catalina 30 MKIII Chicago
I picked up a boat that had been on the hard for a couple of years. We splashed and found some blackflow into the bowl when the boat is left for a few days. Joker valve was just replaced but we havent been back since. We also discovered that the handle to pump the head would pop back up unless the pump out cap was unscrewed so we had the vent cleared out. The head is only a few years old and the lines were also replaced. The holding tank however, is 30 years old. We are currently using Odorlos as a treatment even though I didn't have the best experience with it on my last boat. I'm curious if we would benefit from something like Noflex digestor or another more intensive cleaning product to clean the old tank or as a preventative measure. The head stinks last time we were on board!
 
Jan 4, 2006
7,281
Hunter 310 West Vancouver, B.C.
I'm curious if we would benefit from something like Noflex digestor or another more intensive cleaning product to clean the old tank or as a preventative measure. The head stinks last time we were on board!
No relationship at all.

The holding tank is (should be) completely sealed. The contents, no matter how foul, are not causing the external smell . Look for a leak somewhere else.

Joker valve was just replaced but we havent been back since.
If that's still leaking, there's one possible source of odour.

The head is only a few years old and the lines were also replaced.
Are the lines a good quality hose.
 
Feb 26, 2004
23,054
Catalina 34 224 Maple Bay, BC, Canada
The head stinks last time we were on board!
Many of us have used the head sink drain tapped into the head input so as to use fresh water for the LAST flush before leaving the boat, discussed here many times. The smell could well have come from seawater sitting in the head when you're gone (although your lake is not salt water). So you've got some backup from your holding tank somewhere. How long since you pumped out?
 
Sep 24, 2018
3,437
Catalina 30 MKIII Chicago
The joker valve was leaking and the vent for the tank was clogged. we have not been back since these items have been taken care of. The hoses are good quality but not top notch. I do not remember the model off the top of my head. Will the contents of the holding tank smell if properly treated?
 
Jan 4, 2006
7,281
Hunter 310 West Vancouver, B.C.
Will the contents of the holding tank smell if properly treated?
We're told that the contents of an aerobic (properly treated) holding tank will mostly give off methane and CO2 both of which are odorless.

But I hope you're not looking at odorless sewage as being a solution for your smelly problem :yikes: :

1754248458253.png

I don't know if the guests would approve.
 
Dec 2, 1997
8,950
- - LIttle Rock
O
We're told that the contents of an aerobic (properly treated) holding tank will mostly give off methane and CO2 both of which are odorless.
You're told by WHOM??? Definitely not by me! It's oxygen, not treatment, that creates the aerobic conditions necessary to prevent odor from being created. Methane IS odorless, but is an anaerobic flammable gas. CO2 is aerobic but is heavier than air, so without enough air exchange via the tank vent or an aerator, it can blanket the contents of a holding tank, turning them anaerobic.
There are a couple of tank products--NoFlex Digestor is the best, Odorlos is another--that can work with less oxygen than others, but there is no tank product that can prevent odor completely without any.

--Peggie
 
Sep 24, 2018
3,437
Catalina 30 MKIII Chicago
O


You're told by WHOM??? Definitely not by me! It's oxygen, not treatment, that creates the aerobic conditions necessary to prevent odor from being created. Methane IS odorless, but is an anaerobic flammable gas. CO2 is aerobic but is heavier than air, so without enough air exchange via the tank vent or an aerator, it can blanket the contents of a holding tank, turning them anaerobic.
There are a couple of tank products--NoFlex Digestor is the best, Odorlos is another--that can work with less oxygen than others, but there is no tank product that can prevent odor completely without any.

--Peggie
Are you recommending Digestor over Odorlos? How would one determine if there's a layer of anaerobic gas, aside from a stinky head which could be caused by a few different issues?
 
Jan 4, 2006
7,281
Hunter 310 West Vancouver, B.C.
But, but, but, that's exactly what I mean.

The holding tank contents are "properly treated" by the unspoken, the vent lines, which supply air (which is about 21% O2) to promote aeorobic decomposition. There are other means (chemical) of getting O2 into the contents but this is the simplest and cheapest. Cheap is the reason I choose to use vents rather tham chemicals. And speaking of cheap, I always take my eyeglasses off when I'm not looking at anything so as not to wear them out.

And as you say, because CO2 requires a little motivation to keep moving along, dual vent lines are better than just a single vent line :

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The forward vent hose is connected to an above the waterline thru-hull at the beam of the boat and the aft vent hose exits at the aft end of the hull which sees slightly negative air pressure while under way.
 

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Jan 7, 2011
5,659
Oday 322 East Chicago, IN
I picked up a boat that had been on the hard for a couple of years. We splashed and found some blackflow into the bowl when the boat is left for a few days. Joker valve was just replaced but we havent been back since. We also discovered that the handle to pump the head would pop back up unless the pump out cap was unscrewed so we had the vent cleared out. The head is only a few years old and the lines were also replaced. The holding tank however, is 30 years old. We are currently using Odorlos as a treatment even though I didn't have the best experience with it on my last boat. I'm curious if we would benefit from something like Noflex digestor or another more intensive cleaning product to clean the old tank or as a preventative measure. The head stinks last time we were on board!
I put ice cubes and some detergent along with some water and sailed the boat for a few weeks (the ice cubes only work for the first day :facepalm:). The idea is that the cubes help “ scrub the inside of the tank, detergent and water softener any hard “crap”in the tank. Sail it is as lumpy seas as you can stand!

After that, pump out and hopefully the tank is cleaner than it was.

Alternately, I have removed my tank, took it home to rebed the various fitting that were screwed into bosses. A few were leaky, leading to my smelly aft cabin. I removed the fittings, blasted the inside of the tank with pressure washer, got it as clean as I could and reinstalled the fittings. Made a huge difference (probably mostly by fixing the leaks).

Greg
 
Dec 2, 1997
8,950
- - LIttle Rock
Dual vent lines are NOT the best way to increase air exchange in the tank and chemicals aren't an alternative...a few are just able to work with less air exchange. A single vent will work just fine IF:
a) it's short (no longer than 5-7', straight and doesn't rise more sharply than 45 degrees.
b) the "vent" thru-hull is replaced with an open bulkhead (aka "mushroom") fitting that will let the tank "breathe"..."vent" thru-hulls do not.
Aeration is a much better choice than a second vent and doesn't have to be expensive...many boat owners are DYI-ing aerators using a bait tank pump and a perforated (poke holes in the top of it) piece of hose run across the tank near the bottom of it. To work, aerators MUST run 24-7-365 whether you're on the boat or not, but the current draw is very low. When not running the tank will quickly turn anaerobic, forcing stinky gasses out the vent when it's turned back on that can take several hours to slowly improve.

-Peggie
 
Jun 11, 2004
1,776
Oday 31 Redondo Beach
If the holding tank contents stink the odor should only come out of the vent line. The contents of the holding tank stinking should not mean that the head compartment or toilet stink. A la Ralph Johnstone in reply 2. Right?

So if your head compartment smells it is likely leaks in the fittings, permeated hoses, or as Stu said in post 3, stinky dead stuff that has been sitting in the intake lines and toilet bowl channels while you are away and not exercising the toilet pump. Even "fresh" lake water will have organisms that will die and smell when trapped in the intake.

If you flush thoroughly, even small backflow through the joker valve shouldn't cause (much) odor because the backflow should be clean water.