# Coming from RV to boats. Do you use holding tank chemicals?



## serpa4 (Aug 2, 2015)

In my RV's I use holding tank chemicals. Either enzyme based to digest and break down waste or stuff to keep it from smelling. I'll be full time liveaboard, and plan to pump 1-2 times per month. I'll avoid solid waste, but it will happen in the middle of the nights I predict.
Do you use chemicals or what controls order and breakdown of TP and waste?


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## Lake Superior Sailor (Aug 23, 2011)

Same as the camper!....Dale


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## IStream (Dec 15, 2013)

Yup, but there's still plenty of stuff that doesn't work. I'm a fan of Happy Campers:

https://www.amazon.com/gp/product/B007S0LDME/ref=oh_aui_search_detailpage?ie=UTF8&psc=1


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## eherlihy (Jan 2, 2007)

Many people swear by K.O.... 









I use SeaLand Holding Tank Deodorant;


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## Stu Jackson (Jul 28, 2001)

The New Get Rid of Boat Odors

KO or Odorlos


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## zeehag (Nov 16, 2008)

odorlos.
best stuff on planet
donot put tp into your holding tank unless you want a foul mess. bag it


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## IStream (Dec 15, 2013)

I'd rather have a foul mess in my tank than in bags out where I can see/smell them.


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## pdqaltair (Nov 14, 2008)

Just as much fun as an anchor thread, but smellier!

1. There is a no-TP cult. If that is too gross for you, the trick is to make certain to use single ply (Scott is best in testing) and flush enough water to keep liquid.
2. Do NOT use the blue deodorizing chemicals. They don't work and are bad for the hoses. Do use something containing nitrate, like Oderlos. The enzyme treatments seem to work too.
3. Flush the vent once in a while. They tend to plug with c__p due to healing and too full tanks.
4. Post a sign in the head for guests saying what not to flush and how to operate.


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## travlin-easy (Dec 24, 2010)

I used Rid-X while in the Florida keys and it seemed to do a great job. Doesn't take very much when your holding tank is just 30 gallons. 

I agree on flushing or cleaning the vents regularly. In my case, mud daubers decided it would be a great place to call home and packed it solid with mud. I then found a new fitting that had a screen so they couldn't get into the hose and fitting - they still packed the damned thing, only this time, on the outside edge of the screen. Finally, I put a few drops of Avon Skin So Soft on the screen and they stayed away.

If your vent gets clogged, you could end up with a collapsed holding tank during pump-out. The pump-out boats in the Florida Keys had very powerful, gasoline engines that ran the vacuum pumps, which could easily collapse a quality stainless holding tank in a matter of seconds.

Play it safe,

Gary


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## pdqaltair (Nov 14, 2008)

eherlihy said:


> Many people swear by K.O....
> 
> 
> 
> ...


I tested a lot of these side-by-side using a row of matching holding tanks for Practical Sailor. Sealand, as I recall, finished dead last. You can do better with other forum suggestions, I promise. This one is also rough on hoses.

Ridex also did poorly, is rated poor by everyone, and is not recommended for this purpose by the maker. There are better products.


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## outbound (Dec 3, 2012)

Was taught all the chemicals are ultimately bad for the system. Only exception may be adding bacteria to speed things along. Since doing nothing my through hulls don't need to be exercised as often and there's no stink. 
Was taught when possible to use fresh water for flushing. Then the bacteria in your gut will continue to survive in the holding tank and digest your poop. Using salt changes the flora dramatically and makes it more stinky. So we use salt flushes on passage or when off the grid but fresh in the good old US of A. When changing from salt to fresh do a pump out, then add some freshwater and bacteria and back in business.

Please note I'm the same old PITA Outbound. The new sign in rules had me stimied. After waiting days for a response from this site just gave up and reregistered under a new name. If the the moderators are reading this sure would like my old profile and name restored. Please PM me and give this clueless poster instructions on how to do this.


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## Minnewaska (Feb 21, 2010)

Chemicals that mask odor, ultimately cause odor. Not to mention, they have to be bad for the environment, wherever you ultimately dispose of your holding tank. Even a pump out ends up in the ground somewhere.

The concept is to maintain a healthy tank, with plenty of oxygen and nothing that will kill the good aerobic bacteria that break down waste and do not smell. Oil, chemicals and lack of oxygen are what kill these good bacteria and allow the anaerobic bacteria, which we all relate to smelly sewage, to thrive.

I've never had trouble flushing TP, but you have to use it sparingly. Most critically, you have to flush a full bowl of clear water behind your waste to push it all through the piping and into your tank. Too many just think its gone, when out of the bowl, but the paper is really sitting in the line behind your head and will settle back down to the bottom, if you didn't push it through. This is the cause of most cloggings, not using too much in the first place.

I supplemented by tank with KO for years, but switched to Happy Camper last season. It's substantially less expensive, however, I find it better to mix with water first. KO comes as a liquid. I also recall KO had an expiration date, but I haven't seen one on HC.

I also clean the bowls with CP cleaner, which won't kill tank bacteria. I bet many clean with a bleach based cleaner, which would destroy bacteria on the next flush. We use bleach on the walls, counter tops, etc, but never in the bowl.


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## travlin-easy (Dec 24, 2010)

Essentially, there is little or no oxygen in your holding tank. The bacteria active in a septic or holding tank are anaerobic. Anaerobic means the bacteria operate without oxygen from the air. The result of their anaerobic activity generates odors, the most common of which is hydrogen sulfide gas. The other gas, of course, is methane.

Gary


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## newt (Mar 15, 2008)

Just sail beyond the limit for dumping once or twice a month and use the gator. BTW I don't add anything.


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## pdqaltair (Nov 14, 2008)

Minniwaska, Outbound 50, you were taught incorrectly, or at least incompletely.

"Chemicals" is too broad a term to be useful in conversation and you know it. Water is a chemical, as is steel or air. We won't use it, not without adjectives.

Traditional "chemicals" were often intended to sterilize or mask, and were either highly caustic (alkaline, like lime) or antiseptic (formaldehyde and relations). The former can increase tank deposits, the latter is bad for hoses, and both stink and don't really work.

The current generation is based primarily on nitrate (NO3-). In the absence of atmospheric O2, bacteria use sulfate (SO4-2) as an oxygen source (that is an over simplification, but we'll run with it), generating hydrogen sulfide (stink) in the process. By adding nitrate we give them an alternative oxygen source that does NOT generate stink. Nitrate is harmless to all materials, non-toxic, cheap, and very effective.

There are a few enzyme-based formulations that work very well, though some have a lot of nitrate in them too. Which is fine.

The reason freshwater flush helps is that seawater is high in sulfate and freshwater is not. No sulfur source. Simple.

So yes, the new "chemicals" do work and are recommended even for folks that dump, because they will reduce hose permiation. However, they need to be the right ones. Look for nitrate in the ingredients, or just by Oderlos (essentially NaNO3).

Solutions for a Stinky Holding Tank - Practical Sailor Print Edition Article


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## eherlihy (Jan 2, 2007)

pdqaltair said:


> I tested a lot of these side-by-side using a row of matching holding tanks for Practical Sailor. Sealand, as I recall, finished dead last. You can do better with other forum suggestions, I promise. This one is also rough on hoses.
> 
> Ridex also did poorly, is rated poor by everyone, and is not recommended for this purpose by the maker. There are better products.


I believe that each boat owner has to make their own decision based on what works with their holding tank system.

My system uses fresh (not sea) water to flush. It is a Vacuflush head, plumbed with a combination of rigid schedule 80 PVC, and Trident 101 flexible hose. Because my fresh water tanks contain chlorine, which kills off the good bacteria, enzyme based products like KO (which wasn't tested in the Practical Sailor article BTW) won't work for me.

I tell guests to feel free to use the head, and demonstrate how to use it, but I warn them that if the system is used, we will pump out before I put the boat back in her slip. Leaving the holding tank full for an extended period (like 5 days) is a guarantee that your boat will develop head odor. I have only pumped out once this year.

I teach sailing on the school boats, and my sanitation and holding tank system does not get the exercise that it used to get, because I am using their holding tank. I add about ¼ of the recommended dose, or ½ an ounce, for my 15 gallon holding tank. The 15 gallon tank is usually sufficient capacity, with the Vacuflush head, for 2 people for a week. My main concerns are breaking down any TP and solids that may eventually find their way into the tank. Quoting the February 2012 PS article;



> Chemical treatments that relied on disinfection, surfactants, and deodorants were generally better than nothing, and they did a serviceable job of reducing solids.


So it seems that the Sealand stuff is the right choice for me.

Finally, when I bought the boat, there was a supply of the Sealand chemical aboard. In fact, I don't think that I've ever replenished it!


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## Minnewaska (Feb 21, 2010)

eherlihy said:


> ......enzyme based products like KO (which wasn't tested in the Practical Sailor article BTW)...


This is a fundemental issue I have with PS testing. They frequently leave out a mainstream product or use incomparable versions of competing products and still draw a "best" conclusion. When testing cordage, they used different diameters of different brands



> I warn them that if the system is used, we will pump out before I put the boat back in her slip. Leaving the holding tank full for an extended period (like 5 days) is a guarantee that your boat will develop head odor. I have only pumped out once this year.


Curious, why is using the head, let alone pumping out, a warning? Hard to stay properly hydrated, if no one needs the head. Only used once all year?

Pumping out, flushing with clean water, then pumping out again, is best. However, I believe it's ones hoses that typically smell, not the tank. Often, the holding tank isn't even in the head, so if that the location of odor, it's clearly not the tank. Leaving some urine in the tank for a week, with hoses you are certain contain clear water, is not going to smell.


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## eherlihy (Jan 2, 2007)

Minnewaska said:


> Curious, why is using the head, let alone pumping out, a warning? Hard to stay properly hydrated, if no one needs the head. Only used once all year?


While we are at the dock part of my pre-sail briefing runs along these lines; 1 - here is where I keep the drinking water, 2 - the bathrooms at the marina are right there, 3 - here is how to use the head, 4 - feel free to use the head, but if you do, we are going to pump out when we return.

For a daysail, this seems to disuade most people... and I'm fine with that.:devil


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## Minnewaska (Feb 21, 2010)

eherlihy said:


> While we are at the dock part of my pre-sail briefing runs along these lines; 1 - here is where I keep the drinking water, 2 - the bathrooms at the marina are right there, 3 - here is how to use the head, 4 - feel free to use the head, but if you do, we are going to pump out when we return.
> 
> For a daysail, this seems to disuade most people... and I'm fine with that.:devil


Your call. Obviously, you want to send a "please don't use it" subliminal message, which is working, since it was reportedly used once all year. What the big deal to pump out? Too much time?


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## eherlihy (Jan 2, 2007)

Nope, the head hasn't been used at all, and the holding tank has only been pumped out once *this* year (since May - the season is less than ½ over). I actually have no problem with anyone using the head (as long as the guys sit, and everyone closes the seat when through). The one time that we did pump out, it was only water that was being pumped out.

Perhaps my choice of words could have been better... I _advise_ people that if we use the head, we will pump out.


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## outbound (Dec 3, 2012)

As usual Ed demonstrates the difference between knowledge and wisdom. Again quote Perry-"different boats for different folks". 

Where we are at present we have a pump out flag and unlimited fresh water. Pump out boat comes to the slip twice a week. So fresh water and no chemicals means no stink. Both heads have macerators although only back head is electric. Particle size is small. Tanks are large and rarely if ever filled beyond 1/2 full so they slosh and I think between that and large vents there is some 02 in effluent. But they are mostly empty.
When we are cruising we are like Newt and just go out. When we are south there are no restrictions so the through hulls stay open for 1/2 the year. 
Have found it worthwhile when there's a lull (late evening) on a weekday to periodically pump out both tanks then fill with fresh water then pump out again. Also find it worth while to repetitive run head or manually flush front head periodically with just fresh water when ever water is not an issue. Agree the plumbing more than the tank is the common issue. Would also note I think inadequate venting is a common culprit. If adequate venting is present off gassing will leave by the vent. Many systems would benefit from larger or multiple vents. 
PDQ respect your knowledge and have a working knowledge of microbiology from prior schooling but respect Minnie's and Ed's wisdom as well.


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## newt (Mar 15, 2008)

Outbound, I think you have described what most people I know do. The only thing I would add is I watch what the locals do in different countries and emulate. If I stop for fuel or a marina, the first thing I find is the head. Offshore is a completely different story. Thanks for the summary.


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## pdqaltair (Nov 14, 2008)

Minnewaska said:


> This is a fundemental issue I have with PS testing. They frequently leave out a mainstream product or use incomparable versions of competing products and still draw a "best" conclusion. When testing cordage, they used different diameters of different brands
> 
> Curious, why is using the head, let alone pumping out, a warning? Hard to stay properly hydrated, if no one needs the head. Only used once all year?
> 
> Pumping out, flushing with clean water, then pumping out again, is best. However, I believe it's ones hoses that typically smell, not the tank. Often, the holding tank isn't even in the head, so if that the location of odor, it's clearly not the tank. Leaving some urine in the tank for a week, with hoses you are certain contain clear water, is not going to smell.


KO was tested in a subsequent round and did very well. No PS slight intended, just didn't make the first round.

By the way, the best way to get a product tested at PS is the ASK. They will nearly always do a second round if someone asks. There are a LOT of brands out there and testing is expensive.

---

Seawater and freshwater are very different. Stands to reason the answers are a little different. I always use a freshwater flush unless I foresee a water shortage, which is not even every season. Still I would suggest exercising the seawater valve a few times a year.

---

As for cajoling guests into not using the head, I can't see myself doing that. They are my guests. And I don't see the need to pump out every time; it's not like you are actually going to get it empty, and who cares?


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## outbound (Dec 3, 2012)

By far and away the worse through hull to exercise is the head exhaust. Please explain to me why that is on every boat I've ever owned they are the ones that get stiff first. Is just because we are feeding the sea life through them. Have learned to excercise them weekly to prevent trouble. Would like to learn if there is anything I can do to prevent them from getting stiff? Doesn't seem to matter if left open or closed. Just don't understand this.


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## eherlihy (Jan 2, 2007)

pdqaltair said:


> As for cajoling guests into not using the head, I can't see myself doing that. They are my guests. And I don't see the need to pump out every time; it's not like you are actually going to get it empty, and who cares?


Leaving effluent in the holding tank for over a week (especially with a Vacuflush system, because it uses so little water) will cause holding tank odor.

Because I am not at the boat every day and I keep my boat in a NDZ, I pump out, then rinse with a couple of gallons of fresh water, and pump again _every_ time the head is used, unless I am on a cruise. When on a cruise, I don't use chemicals, and dump at sea. When I return, I pump out, rinse, and then add ½ an ounce to the system again.

Also in the article on enzymatic additives in PS ("Fighting Odors with Chemicals Part II" - December 2012), of the 7 holding tank additives, the only one not recommended was Rid-X. Prices ranged from 2-8 cents per treated gallon.

Finally, I don't have an issue with my through hull for the macerator discharge. It is as stiff as the rest of them.


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## travlin-easy (Dec 24, 2010)

The only odor I've ever had was when the hoses, which were 30 years old at the time, began to permeate. My holding tank is welded stainless, thus no chance of permeation there. I changed all the hoses about 4 years ago, installed a new "Y" valve, and never had a problem since, other than the damned mud daubers plugging up the vent. 

I wonder why Rid-X was not recommended for holding tank use, when it is highly recommended for septic tank use? Inquiring minds would like to know.

Gary


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## wsmurdoch (Jan 23, 2007)

In Practical Sailor's February 2012 article "Solutions to a Stinky Head" they did not test formaldehyde holding tank treatments dismissing them out of hand for chemical concerns. Tetford calls its Aqua-Kem Liquid "The most powerful odor control available". It was not tested. 

I thought the testing should have included a formaldehyde odor control agent as a base case. Without it, to call one of the other products "best" does not seem right.

That said, I used sodium nitrate fertilizer (16-0-0) and a little detergent for six months on our trip to the Bahamas this year with good results. It is really cheap.


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## Minnewaska (Feb 21, 2010)

I flush with seawater. When I leave the boat, I flush one bowl of freshwater provided by the sink faucet next to it. This way, the seawater in the hose does not sit around and rot. 

As for seawater in the tank, there just isn't a chance that my tank will permeate. It's all about the hoses. 

If you are actively using your head this makes even less difference.


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## pdqaltair (Nov 14, 2008)

wsmurdoch said:


> In Practical Sailor's February 2012 article "Solutions to a Stinky Head" they did not test formaldehyde holding tank treatments dismissing them out of hand for chemical concerns. Tetford calls its Aqua-Kem Liquid "The most powerful odor control available". It was not tested.
> 
> I thought the testing should have included a formaldehyde odor control agent as a base case. Without it, to call one of the other products "best" does not seem right.
> 
> That said, I used sodium nitrate fertilizer (16-0-0) and a little detergent for six months on our trip to the Bahamas this year with good results. It is really cheap.


KO and CP were both tested (PS Dec 2012).
Aqua-Kem was tested (PS Feb 2012)

I'm guessing these articles were not carefully reviewed. I just looked them both up.

*PS tested:*

BacTank #
Rid-x 
No-flex
Happy Camper
KO
CP
Forespar Refresh
Oderlos 
Camco Ultra
Camco Enzyme
Thetfor Ecosmart
Marine Digest-It

*Plus 2 old school blue chemicals:*
Sealand Max control (contains formaldahyde)
Thetford Aqua-Kem (contains formaldahye)

I think this is a fairly comprehensive list. I don't understand the criticisms.


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## outbound (Dec 3, 2012)

So at the end of the day what I abstract is:

A good system with best practice hoses, excellent open ventilation that uses fresh water as often as possibly and has fresh clean water left in all plumbing after use requires NO additives of any sort. Also leaving tank(s) empty, having them periodically flushed and avoiding enough time between pump outs for settling to occur is beneficial.

If above cannot be achieved then a O2 source such as a reduced nitrate may help as may enzymatic decomposing agents. If system is sterilized adding bacteria may help. Reading Ms. Head's treatise (forgot her name but she has the real poop) on this subject is highly informative. If someone recalls her name please share.

Importantly avoid any cidal additives or cleaning agents. Avoid dense lumps or high concentrations of cellulose.

If smell is severe or persistent it probably needs to be re-engineered to become a "good " system as need for additives suggest inadequate design or effects of aging and need for replacement of various components.

Lastly gentleman sit to pee and there's nothing funny about a joker valve.

I've heard of folks using vinegar to decrease Ca+2 deposits and cooking oil to lubricate valves. Given acetic acid can run through the Krebs cycle and the small amount of oil probably has no deleterious effect suppose this is benign. But would be interested if there is any hard data on risk/benefit of these additives.


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## wsmurdoch (Jan 23, 2007)

pdqaltair said:


> Aqua-Kem was tested (PS Feb 2012)
> 
> I'm guessing these articles were not carefully reviewed. I just looked them both up. .... I don't understand the criticisms.


You are correct. I was wrong. I misinterpreted Practical Sailor's comments in the second paragraph of the February 2012 article.


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## eherlihy (Jan 2, 2007)

outbound said:


> So at the end of the day what I abstract is:
> 
> A good system with best practice hoses, excellent open ventilation that uses fresh water as often as possibly and has fresh clean water left in all plumbing after use requires NO additives of any sort. Also leaving tank(s) empty, having them periodically flushed and avoiding enough time between pump outs for settling to occur is beneficial.
> 
> ...


Lee,

Thanks for the summary. The "queen of boat odors" is Peggy Hall.


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## Minnewaska (Feb 21, 2010)

eherlihy said:


> Lee,
> 
> Thanks for the summary. The "queen of boat odors" is Peggy Hall.


I believe she goes by Head Mistress. Clever.


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## Don L (Aug 8, 2008)

I leave my boat on mooring all week with poo in the tanks without chemical and the only odor I have is during the first flush when I return due to the dead sealife in the flush water line. That odor is in the head itself inside the boat. So I just flush it real hard that first use when I come back to the boat and get it over with.


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## Riptides (Jul 13, 2016)

If you don't mind a new user butting in, but has anyone considered or has used a bidet style attachment or "butt gun" sprayer in lieu of paper? I see folks mentioning extra water to flush paper, or bagging it *eww*. In this case paper could be used to dab dry, and then bagged, but would be a bit more sanitary and less *eww*. I understand (fresh) water is precious when sailing, but a little spray, dab, bag and go seems better than worrying over clogs and solids.


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