Best way to help reduce black tank odors.

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CP

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Jan 12, 2012
Posts
131
Just wondering what others do to help reduce black tank odor?
Not expecting to be greeted with the most pleasant of odors after flushing in the MH (2011 Fleetwood Terra)?
But we are certainly open for ideas to help reduce odors. Currently we are only using Pure Power waste digester and odor eliminator in the tank as recommended.

Thanks in advance!
Chuck
 
The first thing to do is to stop using the chemicals. They are not solving the problem, they are covering it up. If you do it right you won't need chemicals at all. What you do need is water, lots and lots of water. When I dump my black tank I put about five gallons in it to start with. Every time I use the toilet I hold down the flush lever and count to five. That's all you got to do.

Now if you are boondocking then you will need to dump the tanks when they are at least 3/4 full. Don't dump with any less than that or it won't take all the solids out of the tank. If you are hooked up to a sewer then keep the grey valve open at all times but keep the black valve closed until the tank is at least 3/4 full, then dump, then close the valve again.

If you have been hooked up to a sewer and keeping the black valve open you might have developed a poop pyramid when the poop lands in the tank and doesn't get flushed down the sewer line. If you do have a poop pyramid it could take an effort to remove it.

Bottom line, you should not have any odors coming from your toilet without chemicals. Actually I do dump a few squirts of Dawn dishwashing liquid into the black tank after dumping to give the toilet a sweet smell.
 
Turn off your exhaust fan while flushing, use plenty of water while flushing, wait to dump until you are 1/2 to 3/4 full and do nothing else.
 
Are the flush seal holding the water OK after you flush? That inch or so helps keep the odors where they belong. There was/is another topic with that subject if I recall.
 
The black tank and toilet smelled terrible when I bought my used 5th wheel. I discovered that I had the dreaded poop pyramid, the previous owner obviously had little experience with an RV tank. So the first thing I did was empty the tank as best I could, I was in an RV Park with hookups, so I was able to dump....then I filled the tank with a full hot water tank of hot water....and added some dawn dishwashing liquid, not too much just a good long squirt. Went to bed.

The next morning I was traveling so I emptied the hot water heater again in the toilet. Now the blackwater tank was almost 3/4 full. I pulled out and stopped at the park office and bought two large bags of ice. I dumped both bags of ice in the toilet and then drove for about 100 miles....when I arrived at the park I hooked up and dumped the blackwater tank, then I filled the tank with another hot water heater full of hot water, another squirt of Dawn dishwashing liquid and then filled the tank back up to 3/4 and dumped it again.

It has not smelled since in two years and I use plenty of water when flushing and only empty when at least 3/4 full. I never leave the back valve open when on sewer hook-ups, I actually keep both my grey and blackwater closed and dump when nearly full. I leave the hose hooked up but the gate valves closed. I dump the black first and when that is finished I dump the grey to flush the hose out.

I have never had the need to use any chemicals and doubt I ever will. I can even leave the fan running when I flush and don't get an odor, at least nothing worse than what I just put in!!!

I have a four flush rule in my RV. Fill the bowl, do your business, flush and fill the bowl three more times and flush.


Good Luck.

Jim
 
What everybody else says.  I used to use chemicals and dealt with odor often.  Since I quit adding anything except water, it has been odor-free.  Use water only.  Plenty of it and dump when it's 3/4 full.  Easy.
 
Thanks everyone for your help.  I added lots of water and nearing the point to dump black tank.
Hopefully things will come up Rosie (or something like that).

Thanks again.
Chuck
 
Pure Power is a good product and not causing your problem, but more chemicals won't help either. You could have the poop pyramid problem if the black tank has been used with no water in it, i.e. the drain valve was left open. It needs to have liquid in the tank for the solids to dissolve and the waste & odor eating bacteria to thrive. Otherwise, I don't think that is the problem.  And while you should use adequate water to flush, I don't think you need to go overboard either. A normal single flush works fine for us.

There should be no smell at all when you flush, so something is clearly wrong. My first step would be a thorough rinse, fill and drain the tank a couple of times and use a tank rinse tool if you have one. Then I would fill the waste tanks (gray & black) with fresh water and add a enzyme-based septic treatment and let it sit for 3-5 days and then dump and rinse and dump again. I like the Roebic K57 or Rid-Ex enzyme products for cleaning, but your Pure Power is probably ok too. See if that gets rid of the ongoing odor problem.
 
You might also want to invest in an "RV Hydroflush" extension for your tank output hose.  Helps you see (literally) what is rushing out of the tank... sounds gross but is actually helpful... and allows for a backflushing of the tank by connecting a hose from the outside.
 
Chuck,
If you don't have enough in the black tank to flush, but want to, you can always add water until you are at the 3/4 point and then do it.  That way you have plenty of fluids to escort the contents out.
 
I have never reallly noticed a serious black tank odor issue.. Even when I had the toilet off fixing it so the tank was open.

EXCEPT For one time.. That one time I'd dumped tanks and FORGOT to close the valve.

Now the gray tank.. With all that food and grease in it.. That gets downright stinky.

But not so much the black.

The best advice I can add to what is above (I don't like chemicals eiother and don't use 'em) is close the stinking valve.  OR.. Trap the line..more on that.

Some places have rules that state the hose must slope toward the hole in the ground (no low spots) if this is the case you can not trap it.

I have 3 tanks.

Black, Gray and Wash (The wash tank does NOT get any water from the kitchen sink, only bathroom lav's and shower)  This last tank I normally drain via a 3/4" Garden hose (Also gray, gray hose = Gray water, color coded,, Yes I have a black garden hose too, and a macerator pump for those cases where it's needed).

Back to topic... That hose, needing only abourt a one inch rise to "Trap": I do leave open. (Wel;l the dump valve)

But the big hose I close the valves and no problem.. The one time I left ;'em open, big stink.
 
Another good way to get complete dumping of the black tank is to drain it first and then open the gray tank valve and allow it to backflush into the black tank so that the soapy residues from the gray tank can act on the black tank contents. I usually let it work for about five minutes before dumping the whole thing. Only works if you have a pumpout system. Jack
 
Jack Siegrist said:
Another good way to get complete dumping of the black tank is to drain it first and then open the gray tank valve and allow it to backflush into the black tank so that the soapy residues from the gray tank can act on the black tank contents. I usually let it work for about five minutes before dumping the whole thing. Only works if you have a pumpout system. Jack

I don't think I've ever heard of this method... but it just might work?  I'm thinking of a typical "1 drain" system where the two tanks outlets come together.  Drain the black tank, keep the black valve open, replace the drain cap, and open the gray valve.  The only potential issue would be if you have a larger gray tank than black tank, with the risk of overflow up through the toilet as the gray water fills up the black tank.
 
scottydl said:
I don't think I've ever heard of this method... but it just might work?

    It "does" work, Scotty, and has become standard procedure for me. That is why I make sure I always have a full gray tank when ready to dump the black tank - vs. always leaving the gray line open while in a park. I have a macerator installed so replacing the cap is not necessary. The outlet is connected to the macerator pump by a short piece of sewer hose, so until turned on, the flow stops at the pump. The short length to the macerator is connected by a clear 45 angle so I can see what is going on during the process.

Yes, it's important to limit the backflow and make sure the gray tank "does" contain water. Otherwise, the backflow will go the other way and that would not be good. Tank dumping is not something to start and do something else while it is happening.  :)
 
Looks like we are good to go now.  I did a good flushing (no pun intended) a couple of times and it made all the difference. I have a feeling we did not have enough water to begin with as I thought we had.

You are all great to help out.  We just bought our first motorhome late last fall and are now on our first trip this season and having a great time (with a little help from our forum friends).

Thanks to all.
Chuck
 
4DogsRV said:
I found this very informative:

http://m.youtube.com/watch?v=gZFyfsy4ptw

By using the gray water to flush out the black tank you can accompliush the same thing as shown in this video but to it in a fraction of the time.

1.) Dump the black and leave the valve open.
2.) Open the gray valve for 3 or 4 seconds. Some gray goes down the drain and some backflushes into the black tank.
3.) Close the gray valve. Watch the black tank drain the gray water back out taking waste that was left from the first draining with it.
4.) Repeat #2 & 3 until black tank runs gray. (Usually only one more time.)
5.) Close black valve and fully drain the remaining gray water.

Simple, quick and easy; you don't need to connect a hose or wait minutes for the tank sprayer to add water to the black tank.

(Edited to correct spelling, typos.)
 
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