Sealand/Dometic TDX holding tank treatment

Am considering using this treatment chemical for my head/holding tank. It’s formaldehyde based and I’m not clear about using it. Pour 8oz into the head and pump, or pour same amount down the Pumpout line? Is this stuff compatible with my Raritan seawater toilet? There seem to be a lot of precautionary warnings about handling this chemical. And does it really work? Reviews claim it will clean hoses and holding tank and eliminate odors completely. Also USCG approved as formaldehyde is biodegradable. I have been using KO enzyme for years and it’s OK at best. Any experience?

Use of formaldehyde is not a good way to go. It is strictly a poison that kills all bacteria, good and bad.
When we were RVing many of the attendants asked to see what you were using. If it was formaldehyde based they would not even let you into the park as it would poison their septic fields.

There are far better treatments out there.
Peggy Hall has written MANY times about this subject in this forum. Look up some of her posts, better is buy her book and read it.

https://www.amazon.com/New-Get-Rid-Boat-Odors-ebook/dp/B01BW2ZSTW



I'm now using a product called NoFlex which is a powder.
https://marinesan.com/noflex-digestor/

There are other good ones also.

Of course look around for better prices as all I doing is highlighting the product.


If the problem is odours then maybe there is a way to help. Peggy has many suggestions in her book,

Peggy Hall is known as Headmistress.

woodscrew said:

Am considering using this treatment chemical for my head/holding tank. It’s formaldehyde based and I’m not clear about using it. Pour 8oz into the head and pump, or pour same amount down the Pumpout line? Is this stuff compatible with my Raritan seawater toilet? There seem to be a lot of precautionary warnings about handling this chemical. And does it really work? Reviews claim it will clean hoses and holding tank and eliminate odors completely. Also USCG approved as formaldehyde is biodegradable. I have been using KO enzyme for years and it’s OK at best. Any experience?

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Why would you put chemicals into the waste stream? With adequate ventilation, there shouldn't be any odor. Is there something else you want to accomplish? As noted by C lectric, chemicals are unwelcome after the waste leaves your boat, so I question why you welcome them on your boat.
Peggy has lots of posts here where she counsels against chemicals.
I used chemicals the first year I had a motorhome, then I read some of Peggy's advice here and stopped doing so. Neither there nor on my boat have I ever had any odor from the toilet, piping, or holding tank. \
No, I do not presently have olfactory failure due to Covid.

Dont bother with any formaldehyde based treatments IMO
With adequate air and water you get aerobic bacteria breakdown which is not smelly. Inadequate air and you get anaerobic breakdown which is smelly.
Larger, shorter, straighter holding tank vent line and a straight mushroom through hull are essential to proper venting. Using sodium percarbonate (generic and inexpensive) or NoFlex (brand name limited sources and more expensive) both work very well and SPC is used by treatment plants for treating sludge.
The other approach is adding a bubbler / aerator to the tank... also works well. Sweet Tank (brand name and $$$) or a DIY bubbler (inexpensive and works well).
See Bacchus website in signature -projects - holding tank aeration project for details of my DIY solution that works very well.
Get a copy of Peggie's (TF Head Mistress) book... everything you need to know about marine heads and more.

SPC on its own was not available to me at all. Maybe if I wanted a truck load.
I may retry my chemical supplier when I next visit them.

I used Oxyclean per O C Divers post as a substitite and then got the Noflex.

Nasty nasty stuff. I hope I never have to hold another bottle. Got a single drop on my hand once and could instantly taste it behind my molars. Not safe. Not ethical to put this into the environment.

Don’t know who thought this treatment up, but I question their judgement.

C lectric said:

SPC on its own was not available to me at all. Maybe if I wanted a truck load.
I may retry my chemical supplier when I next visit them.

I used Oxyclean per O C Divers post as a substitite and then got the Noflex.

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SPC available from multiple vendors on Amazon, Ebay, etc. in almost any quantity great or small.

TDX was never intended to be a holding tank product, it was developed for use in SeaLand Technology (now owned by Dometic) Type I MSD (USCG certified treatment device that was originally named TDX, then called SanX, and finally discontinued more 15 years ago for several reasons, not the least of which was, it barely reduced bacteria count to the legal maximum of 1,000/100 mil, the discharge STANK! and a gallon of TDX--which was about $20 (today it's $35-50 depending on where you buy it) only treated 4 cycles. Dometic/SeaLand continues to market the TDX chemical because there are still a a few surviving SanX systems on boats and because it's almost guaranteed to convince anyone who tries to use it as a holding tank product that they need to install one of Dometic's $100 vent line filters, 'cuz it will NOT eliminate holding tank odor.

It's horrible stuff! We stocked it for a brief while in the '90s till a case came in with a leaking gallon jug...the fumes were so "caustic" I had to move that case outside. And when I called SeaLand for cleanup instructions I was told to treat it as a HAZMAT spill and given HAZMAT cleanup instructions. All of which is the long-winded way of saying "no one should even consider keeping TDX aboard a boat!"

Bacchus gave you the best advice...I recommend you follow it. And I'm always glad to help you figure out how to adapt it to your specific system.

--Peggie

I love it when we get a 100% consensus. I will stay away from this stuff-far away. Thanks for all the replies.

Read Peggy's book.

I am always surprised at the number of letters asking questions about additives, filters, chemicals, etc. which are un needed and the questions answered in Peggy's book.

pete

Thank for the book "plug," Pete. However, my book's title (my publisher's idea) is a bit misleading 'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to operate and maintain your system to prevent 99% of problems instead of having to cure 'em. 'Cuz you get to do any preventive maintenance on your terms when it's convenient...the need to cure a problem never happens when it is!

But it's just human nature to take the easy way out and ask other forum members for solutions to problems instead of doing their own research. That's ok with me 'cuz if everyone did their own research, there'd be no reason for me to be here and I'd miss y'all.

--Peggie

Even though having LOTS of holding tank ventilation seems counterintuitive (more vents "seems" like that might just allow more smell to escape), Peggy is so correct. It reduces the odour, so dont' restrict the air flow in any way. NoFlex (and generic products like it) work well.
However, like Pete and others have said, get Peggy's book. It is well written, with very useable information presented in an easy to understand manner. Prevention is the key and will make your life so much easier. No I am not related to Peggy, just someone who is thankful for all of the help she freely and willingly gives on these forums. She is "good people" as well

Thank you, Tom...I try to be!
You said, Even though having LOTS of holding tank ventilation seems counterintuitive (more vents "seems" like that might just allow more smell to escape), Peggy is so correct. It reduces the odour, so dont' restrict the air flow in any way.

A short course in bio-physics 101 may be useful here:

When organic material breaks down ANAEROBICALLY (without oxygen), it generates hydrogen sulfide and sulfur dioxide which are not only stinky, but highly toxic, and methane which is odorless but flammable...septic tanks are one example.

But when organic material breaks down AEROBICALLy (with oxygen), it converts to CO2 which is odorless. This explains why compost piles must be tossed frequently to aerate--oxygenate--them (otherwise the material just rots and stinks) and why decorative water elements in office buildings and malls always include fountains and/or waterfalls, why mountain streams never stink but swamps do: running water doesn't stink, stagnant water does (and so do wet dirty bilges and inadequately ventilated waste tanks).

So the key to an odorless holding tank (odor out the vent) is plenty of fresh air. In most cases, it can be supplied via a vent line that's short, straight relatively horizontal and has a larger diameter than the standard 5/8" vent line that's also on fuel and water tanks. But tank location and other factors can make it impossible to have a short, straight, horizontal vent line...in which case, aeration may be the only solution. But effective aeration isn't a "one-size-fits all" solution..it has to be designed to push air throughout the tank.

So while larger vent lines and thru-hulls and/or a system that pushes the gasses in the tank out the vent may seem counter-intuitive when it comes to eliminating odor, it's actually just applying plain ol' bio-physics 101.

All this is explained in a lot more detail in my book, the title of which (my publisher's idea) is a bit misleading 'cuz although it does deal with every source of odor on a boat and how to cure, or better yet PREVENT 'em, it's actually a comprehensive "marine toilets and sanitation systems 101" manual that explains the laws, describes all the types of systems and how they work, and will help you learn how to operate and maintain your system to prevent 99% of problems instead of having to cure 'em. 'Cuz you get to do any preventive maintenance on your terms when it's convenient...the need to cure a problem never happens when it is!

And because no book can answer every possible question, I'll do my best to answer any that it doesn't.

--Peggie

Thanks Peggie, another example of what I am talking about..... so much to learn, especially for any newbies.

DDW said:

SPC available from multiple vendors on Amazon, Ebay, etc. in almost any quantity great or small.

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Here in B.C., Canada at least, I have had no success yet.

I deal with a large chemical outfit from time to time for my piddling purchases who may be able to help me. I will ask the next time I am going that way.
It has to be here but no success yet.

None of the US side vendors would ship to me.

Pete Meisinger said:

Read Peggy's book.

I am always surprised at the number of letters asking questions about additives, filters, chemicals, etc. which are un needed and the questions answered in Peggy's book.

pete

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yep, I just finished it a couple weeks ago. Pretty good work on the subject.