Black Water Tank Additives

kwkslvr · Joined: 06 Jun 2006 Posts: 20

We have been using the common formaldehyde-based liquids, but would really prefer something that isn't horribly toxic.
Anyone tried some of the "environment-friendly" additives? What were your results?

Catdave · Joined: 16 Nov 2005 Posts: 120 Location: NC

We've tried just about everything on the market (and spent lots of $$$ in the process) and the ONLY thing that stops the odor when it gets hot is formaldehyde.
_________________
2006 Fleetwood Excursion 39L
Spartan & 350 CAT
FMCA F349619

elh3946 · Joined: 06 Nov 2005 Posts: 1650 Location: Sioux Falls, SD

We've been using Pure Power for several years now and have been very happy with it--and it only takes 2 ounces per 40 gallons compared to 4 ounces of most of the other stuff.

kwkslvr · Joined: 06 Jun 2006 Posts: 20

catdave and elh3946,
S.D. can get VERY hot and Quartzite? yowwie! Then there is the N.C. climate! eeeek!
I think that I might try the organic stuff as I am so unhappy with the poison...

Motor31 · Posted: Mon Jun 12, 2006 10:50 am Post subject:

If you are a full-timer, you do not need to add anything to the tank. If you are a part-timer, make sure you flush the tank thoroughly before you store it, then maybe put some water and an additive in the tank for storage. If you are getting odor in the rig, you may have a blocked tank vent. Check to make sure some critter hasn't blocked it with a nest or something.
_________________
Mike, Nancy and the Fuzzies
2005 MS 38 RL3
2001 Volvo MH (HDT)
2004 R1150RT (piggyback)
1996 Jeep Cherokee (toad)

kwkslvr · Joined: 06 Jun 2006 Posts: 20

Thanks, Motor,
We never store it; use the thing year round. It could very well be that we have something blocking the vent. Will have DH check next time he gets up top.
Only have a real problem if the weather is hot. If we don't have a chance to dump for a week or so, it can be pretty rank.
How much does the additive have to do with breaking t.p. and waste down?

Motor31 · Posted: Mon Jun 12, 2006 4:50 pm Post subject:

The waste already has the enzymes needed to break it down. It came with the waste. A tank in an RV is not really a sewage treatment facility. It's simply a waste holding tank. Putting additives like formadehyde in it kinda kills the enzymes that break the waste down in the sewege system you put it in when you dump. This is particularly so for those systems that depend on a septic tank and leach field.

Really I'd suspect that either your vent pipe has dropped down below liquid leve in the tank or it's been blocked by critters, both of which will stop it venting and push the fumes into the rig. The vent pie has to be above liqid level to work. Sometimes they fall down a bit into the tank. Another possibility that I have experianced is a broke "P" trap in the toilet itself. Some of the less expensive OEM toilets (Thetford in my case) have a small "P" trap built into it that holds water from the flush to help block the tank venting into the toilet. Why I don't know but they do. The trap can get a small hole breaking the vacuum and allowing tank gas to enter the rig through the toilet when it is still closed and not in use. When I got a newer toilet of a differnt Thetford model the odor problem went away on our first rig. The cheap ones can be rebuilt but the cost of the kit and the hassle involved didn't make it worthwhile to me.

If your toilet won't maintain water in the bowl there is another source for your gas leak. The water is a sealant and prevents gas transfer when not in use. If the seal in the bowl is worn or dirty it will allow the water to drain and gas to enter.

We use our black tank for a week (7 days) before we dump and get no odor inside the rig. We also use nothing in the tank but water. When I dump the tank I add about 3 to 5 gallons of water to it before it's used again. I also use the internal spray system to flush it out when it's dumped. I try to make sure the tank is at least 3/4 full before dumping as that helps maintain a clean tank during the flush out.
_________________
Mike, Nancy and the Fuzzies
2005 MS 38 RL3
2001 Volvo MH (HDT)
2004 R1150RT (piggyback)
1996 Jeep Cherokee (toad)

kwkslvr · Joined: 06 Jun 2006 Posts: 20

OK, I see! I will have DH check the vent pipe. Our RV is a 1988 'bago so the pipe may have dropped.
We have to get a new toilet, too. The current one seeps water all the time and fills the bowl up. Had an overflow last weekend. Just water, thankfully, but turning the water pump on and off all the time is not good for it.
I am glad to know that it is NOT necessary to put chemicals in the tank just for normal use. I have been very concerned about the toxicity of the stuff.
Will let you know how this all goes as we work through this.

Catdave · Joined: 16 Nov 2005 Posts: 120 Location: NC

A lot of the information passed on this topic is subjective, as what smells bad to me may or may not bother the next person. However, before you go ripping your whole toilet venting system apart looking for problems that may or may not exist, determine first when the odors are a problem.
Scenario #1:
If your holding tank has waste in it, you have water in the bowl (the toilet is sealed) and you smell odors, this will usually point to one of two things:
a) Your vent tube may have dropped as mentioned, or
b)more likely, the water level has risen to the point that the end of the vent tube is covered, which is completely normal. If this is the case then simply dump the tank, problem solved.

Scenario #2:
If you run the vent fan when doing your business (as everyone on the planet that I know does) then when you flush, the odors are drawn up from the tank and into the motorhome. There is no problem with the system as this is completely normal; the tank is venting in the direction of airflow- i.e. air is drawn in through the toilet vent on top of the motorhome, flows through the tank, into your bathroom, and out through your bathroom fan vent. Even if the fan isn't on odors can easily enter the bathroom when the toilet is flushed through the toilet itself.
This is where toilet chemicals come in- they neutralize the odors so that when they do come into the motorhome they are less fruitful.
What is an acceptable level of smell is subjective- it has been my experience that using nothing is unacceptable. Having tried many different "enviro-friendly" solutions has also proven to be unacceptable. Formaldehyde-based products have been the only thing I've found that truly works in controlling odors. There have been studies conducted ad nauseum as regards the effect of formaldehyde on septic systems, and the impact on a commercial septic system is, according to who's reporting the results, varying degrees of minimal.

As mentioned- the holding tank is not a septic system, it is a temporary holding vessel. You will not usually have the contents in there long enough for nature to run its course and dissolve the wastes, so you simply control the odors till you dump it.
The answer to your question is simple- try nothing.
If that doesn't work, try the enviro-friendly products.
If that doesn't work try formaldehyde.
That will work. Wink

_________________
2006 Fleetwood Excursion 39L
Spartan & 350 CAT
FMCA F349619

kwkslvr · Joined: 06 Jun 2006 Posts: 20

OK, will experiment with this. Once we get the old, leaking toilet replaced, the whole problem might just go away. That would be nice.... *sigh*
All the information everyone has posted is more helpful than you realize. The more I learn about how this all works, the better off I am.
Thank you all so much. Laughing

elh3946 · Joined: 06 Nov 2005 Posts: 1650 Location: Sioux Falls, SD

Jan · Joined: 15 Jun 2006 Posts: 2

I copied this directly from Mark Polk's e-book "The three primary systems
of an RV"

This would be a good time to talk about RV holding tanks. To start with, I would like to mention something about RV holding tanks that I don’t think a lot of RVers are aware of. Many of the free dump stations available to RVers are closing because of chemicals that are harmful to septic systems and because RVers are abusing these dump stations. If we want to have access to these dump stations it is absolutely essential that we use septic safe chemicals (no formaldehyde), and that we clean up after ourselves and do not abuse dump stations.
You should always use environmentally safe chemicals. Enzyme based chemicals use the good bacteria to digest waste and control odors. Formaldehyde based chemicals destroy the bacteria that’s needed to break down waste and they can be dangerous to humans and pets.
_________________
New to it

Catdave · Joined: 16 Nov 2005 Posts: 120 Location: NC

kwkslvr · Joined: 06 Jun 2006 Posts: 20

I just ordered some Pure Power and Micro Power cleaner.
We don't even put chemicals on our lawn or use them in flower beds or gardens so it doesn't make much sense to use them when travelling, does it?

kentullis · Joined: 24 Jun 2006 Posts: 4 Location: wherever it's parked

I had an intermittent problem with odors in my motorhome that drove me crazy.

It turned out that the 3 roof vents for the black and grey tanks used 1.5" PVC tubing but the holes the manufacturer cut in the roof were at least 2"!

Every time there was a slight vacuum in my RV (from using the stove vent or having a downwind window open) the fumes from the vents were sucked back down into the walls of my RV.

The fix was to caulk the openings between the vent pipes and the roof with silicone.

Regards,
Ken