black tank maintenance

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We have been full timers for almost 6 years. We have a 2006 Mandalay model 40 D. I am concerned about the way my husband maintains the holding tanks.  We use RV DIGEST-IT holding tank treatment.  The black tank is emptied every 7 days or more often if needed.  When he empties he flushes the tank for a Max of 5 minutes, sometimes less.  I feel this is totally insufficient.  There is often an offending odor, especially as the weather warms up. We live in Boulder City, NV.  As the days go on the odor is worse. After emptying the tank it improves greatly - then it comes back.  It is most noticeable in the half bath, mid coach streetside.  The toilet empties directly into the black tank.  The rear toilet is a macerating one and there is no odor.  I feel a better rinse, etc. Is prudent.  The tank treatment says DO NOT flush after draining as it removes the necessary bacteria.  Also, the sensors are not accurrate.  He has never used a wand through the toilet to clean the inside if the tank. Any suggestions on this, tank maintenance products would be greatly appreciated. 
 
Sensors are rarely if ever accurate. I think what you are doing wrong is not using enough water. Your husband is doing ok with his procedure. But after he is done does he add at least 5 gallons of fresh water to the black holding tank? Every time you flush do you hold the lever down and count to five? If not then you have probably developed the dreaded "poop pyramid". If so search the forum and you will find instructions on how to deal with a poop pyramid. Basically a whole lot of water is what is needed to keep the black tank odors away. The chemicals really don't do anything for the smell, especially if you are not using enough water. 
 
Don't fret on the sensors....my travel trailer is now a whopping 10 months old.  Guess what already isn't working right?  All of them work fine except for the black tank. 

Your husband's procedure sounds fine.  As the 'Bird mentioned, it sounds like a stalagmite is growing in the tank.  Use lots of water.
 
If your pipe is straight down to the tank, have a look with a flashlight. If there is a pyramid, you will see it.
Make sure the tank is at least 1/2 to 3/4 full before dumping.
And, as noted before, use lots of water...
 
All I've ever done for mine now for the 3 years I've own my RV is when I get home dump the tanks. Then fill them up with fresh water again let then stand awhile and dump again. Sensors always work and no problems and chemicals required.
 
As a simple experiment buy an inexpensive bottle of dish detergent and pour the entire bottle down the toilet after dumping. Fill the tank as full as possible to be able to use it for a few days and then dump when full. Flush again after dumping.


For a couple of bucks we do this a couple of times a year. The detergent helps remove the greasy sludge that builds up on the walls of the tank. If you will be gone fill the tank and let the detergent sit for a week or so.
 
Jeff said:
As a simple experiment buy an inexpensive bottle of dish detergent and pour the entire bottle down the toilet after dumping. Fill the tank as full as possible to be able to use it for a few days and then dump when full. Flush again after dumping.


For a couple of bucks we do this a couple of times a year. The detergent helps remove the greasy sludge that builds up on the walls of the tank. If you will be gone fill the tank and let the detergent sit for a week or so.
Click to expand...

Interesting idea...  8)

I'll have to try that sometime...
 
Another thing that you might want to do is to put a few large bags of ice cubes in the black water tank thru the toilet when on a trip.  The movement of the RV will slosh the ice around the tank.  The ice will melt and flush right out at the next dump.  My sensors work much better after doing this.
 
HueyPilotVN said:
Another thing that you might want to do is to put a few large bags of ice cubes in the black water tank thru the toilet when on a trip.  The movement of the RV will slosh the ice around the tank.  The ice will melt and flush right out at the next dump.  My sensors work much better after doing this.
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I can see the look on the Mrs. face as I'm feeding a bag of ice down the commode...... ;D

Good idea though.  Of course, out here in the Southwest, the ice will be melted before you get out of the campground and back to the highway.  LOL
 
Something I have read on other threads which makes sense to me is; shut off the exhaust vent before you flush. When turned on, it pulls all the odours from the tank when you open the trap on the toilet. I havent tried it yet as mine is in storage for the winter, but I will try it this summer.
 
As a simple experiment buy an inexpensive bottle of dish detergent and pour the entire bottle down the toilet after dumping. Fill the tank as full as possible to be able to use it for a few days and then dump when full. Flush again after dumping.
Click to expand...

Since we have the opportunity to live outside the RV at times, I like to completely fill the black tank with fresh water, dump in a septic treatment enzyme such as Roebic K57 or Rid-X and let it sit for 5-7 days before dumping. Those hungry little microbes do a good job of scouring sludge from the tank walls. I like the K57 because it is designed for cesspools (which is basically what an RV system is), but the K67 or Rid-X seems to work pretty well too.

I do the same thing with the gray tank once in awhile too, to clear away grease slime.
 
Frizlefrak said:
Good idea though.  Of course, out here in the Southwest, the ice will be melted before you get out of the campground and back to the highway.
Click to expand...

Actually you'd be surprised.  A few years ago before we left AZ for TX in our old rig I bought 7 bags of ice in Bouse AZ and dumped 'em down the hole with about a half tank of water.  Our destination was Tombstone which took around eight hours of cruising (we're slow).  When we arrived at the campground in Tombstone I hooked up and pulled the valve and was surprised that there was still quite a bit of ice left in the tank.  Interestingly enough, our sensors then worked great at least for a couple of weeks.  Nowadays I don't bother with cleaning the sensors, I know how we've got on the tank and when it gets close to full it lets me know by burping.

As far as the original post is concerned I've given some thought to a possible problem.  It is the practice of RV manufacturers to NOT glue the vent pipes well if at all.  I'm wondering if you've got a vent pipe dislodged either from the tank or from a joint inside the wall or possibly the exterior stack.  Anything is possible.
 
Well I can't believe it but on my 20 year old Eagle the sensors all work, water, gray tank, black, and LP.  The panel inside shows the status.  Now the panel on the side in the fresh water bay doesn't, but once again when hubby gets time he will fix that too.

The manual says ours has electrical probes in the tanks and that the probes can get coated with grease and not be accurate.  It said if that happens put in soapy water to clean them.
 
Jeff said:
As a simple experiment buy an inexpensive bottle of dish detergent and pour the entire bottle down the toilet after dumping. Fill the tank as full as possible to be able to use it for a few days and then dump when full. Flush again after dumping.


For a couple of bucks we do this a couple of times a year. The detergent helps remove the greasy sludge that builds up on the walls of the tank. If you will be gone fill the tank and let the detergent sit for a week or so.
Click to expand...

This "experiment" really works!!  My black tank sensor never registered "E", 1/3 was always the minimum.  Prior to leaving Tucson, I dumped about 1/4 bottle of dish detergent down into the black tank along with 1/3 tank of fresh water.  Upon arrival in Mesa, 120 miles, I dumped the black water tank and it registered "E". 

Thanks...  I have a new procedure prior to leaving leaving campgrounds.
 
Gonna try this on ours. We have no reading on the black tank at all and a flashlight shows some gunky spots down there. Dern sure worth a try.
 
I can vouche for the Ice and Soap, works like a champ every time.  I had a 2002 32F Winn Adventurer and the sensors still all work for the most part.  What I mean is they indicate the different levels but I would never swear just how accurate they are...lol
 
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