Black tank flushing

[Bnrc73]

I've been reading threads for over two hours now, and I'm more confused than when I started. I'm hoping that simple question will yield simple answers. I've got a2010 3400rl. If I use the black tank flush to fill the tank for a clean out. Can I simply watch for the water to start filling the sewer line in the toilet,shut off the water and pull sewer gate? I don't understand the backflow setup and why they would possible put the valve that if engaged would run Blackwater directly into your trailer.
Second, if filling the black tank directly through the toilet with a hose do I get the same result as filling with the flush line.
Third, what products, natural or chemical, do you use to try and clean the sensors. I Ued CLR in my last TT and it seemed to work. Not so much on my 5ers.
Sorry for the long post, but I feel a stupid question is better than a stupid mistake.

[DQDick]

Your going to get a lot of answers to this as many of us have different beliefs. I've been in a park where someone got distracted while filling a tank with the flush, as a result I will never do that. Another answer you don't want to hear is that I've never found anything that will clean the black tank sensors and keep them clean. On our last rig, I put outside tank sensor on and they worked, but I won't spend that money again since I know when I need to dump without them. I had a black tank valve that leaked and left me needing to clean the tank out good. My dealer recommended filling the tank, adding a product called Commando, letting it sit overnight and that cleaned it out. It's what they use when folks bring them the pyramid of poop.

[1retired06]

Hose in the toilet flushes better and faster than the black flush in my opinion but entails setup time, dragging out a hose, etc.

[BB_TX]

The black tank flush is not meant to fill the tank. It has a spray head to help loosen up any remaining solids that might remain in the tank after the initial draining. I let my tank fully drain. Then I start the flush. After it runs 1-2 minutes I close the drain valve while the flush is still running. After another 1-2 minutes I reopen the drain valve to drain that water with the flush still running. Some additional solids will come out. I close the drain valve and repeat the procedure 2-3-4 times each time the amount of solids is less. Not looking for a “clean” tank. Just getting out most of the remnants.

Just pay attention. Walking away and forgetting the flush is running could end up with a nasty mess.

[richfaa]

What BB Tx said.

[BuilderBob]

I do the same way as BB TX does works good! A way to help get the "crap" off of the sensors is to do a good flush then fill the tank about 1/3 full and dump a bag of Ice cubes in the tank when you are on the road and let them slosh around in the tank and flush it out at your next stop you will be supersized at what comes out!

[kc8lvy]

We Full Time so we have full hook ups. If you do not have full hook ups you may not have time to do this. I use a 15 minute method. Make sure to use a TIMER and do not get distracted.
Make sure grey tanks are closed up 2 days before dumping.
Pull Black tank lever and turn on Black flush for 5 minutes.
START 5 MINUTE TIMER Shut black tank and let fill for 5 minutes or less. While it fills add cheap laundry soap (Low Suds) in the Toilet and flush to clean tank.
After 5 minutes or less is up open black lever dump and let run with flush still on for 5 more minutes.
Turn off Black Flush and close Black tank lever.
Open grey water tank levers and drain grey tanks. This helps clean your hose out.
This works for me but may not for you.

[The Bone]

I drain my tank then with valve open I use the flush for a couple minuets then shut everything off. Then I fill a 5 gallon bucket drop a thingy in the toilet and dump the bucket in the tank. Thats all i do. While driving down the road the water sloshing around cleans the tank. i do that for the gray and galley tank but use a bottole of the blue stuff 1/2 bottle in each tank.

[AZ Traveler]

73,

Your fighting a losing battle to get the sensors clean, if you clean them it is only temporary. A bag of ice down the toilet with a 1/4 to 1/2 tank of water and driving will get them temporarily clean. I just dump every 5-7 days and don't worry about the gauge.

[1retired06]

Originally Posted by AZ Traveler

73,

Your fighting a losing battle to get the sensors clean, if you clean them it is only temporary. A bag of ice down the toilet with a 1/4 to 1/2 tank of water and driving will get them temporarily clean. I just dump every 5-7 days and don't worry about the gauge.

Agree completely sensors are completely unreliable except for the fresh water tank.

[martyperu]

One main thing that confirms flush is a clear elbow in your sewer drain. If you continue flush using method preferred and more or less clear water passing though clear pipe mission accomplished.

[mtlakejim]

What BBTexas said plus the clear elbow Marty suggested. The hose directly into the tank (especially using a wand with jets made for that) probably will do a better job vs the factory installed clean out line but it is a hassle. I use the clean out line thru the season and then the hose and wand before winterizing once a year. Occasionally I will fill the tank about a third with clean water and let it slosh around as I drive to a campsite

[Kyle and Lisa]

Our tank sensors have the same issues and we don't even use the black tank for solids unless absolutely necessary. We always drain all tanks before hitting the road and flush on a regular basis.

[Rondo]

Besides the onboard black tank flush I also connect a clear Flush King reverse flush elbow onto the dump valve and between it and the slinky sewer hose. I connect a separate hose to it (it has it's own backflow valve on it) and use a "Y" at the hydrant. I empty the black tank with the onboard flush going and once I see a reduction in the solids coming out I close the black tank dump valve and let the onboard run for about 5 minutes then open the dump valve again and let it flow out. Once I've done this, I turn off the onboard flush and turn on the Flush King. This sends a stream of water back into the black tank and back flushes from the other direction. I let this run for about 5 minutes and then turn it off and let the black tank empty. It is truly surprising how much more solids I get out of that black tank by doing this. I repeat the Flush King backflow flush several more times and each time the solids and are less and less coming out and the water actually starts to run clear. It sounds like a long process but it sure does clean a tank out. After doing this I dump the gray tanks (kitchen first then the shower to clean out the hose. I then turn on the onboard black tank flush and let it run about 3 minutes to put some water into the black tank and go inside and add a couple scoops of Happy Camper to the black tank and a scoop to each gray tank. As has been stated earlier -- the sensors will never stay clean in any of the tanks and never register correctly once you have put stuff into the tanks. I have use the Commando to no avail however.

[saber707]

Originally Posted by BB_TX

The black tank flush is not meant to fill the tank. It has a spray head to help loosen up any remaining solids that might remain in the tank after the initial draining. I let my tank fully drain. Then I start the flush. After it runs 1-2 minutes I close the drain valve while the flush is still running. After another 1-2 minutes I reopen the drain valve to drain that water with the flush still running. Some additional solids will come out. I close the drain valve and repeat the procedure 2-3-4 times each time the amount of solids is less. Not looking for a “clean” tank. Just getting out most of the remnants.

Just pay attention. Walking away and forgetting the flush is running could end up with a nasty mess.

That is the correct answer and it works well. Just don't leave the water running and unattended.

[saber707]

Originally Posted by Bnrc73

I've been reading threads for over two hours now, and I'm more confused than when I started. I'm hoping that simple question will yield simple answers. I've got a2010 3400rl. If I use the black tank flush to fill the tank for a clean out. Can I simply watch for the water to start filling the sewer line in the toilet,shut off the water and pull sewer gate? I don't understand the backflow setup and why they would possible put the valve that if engaged would run Blackwater directly into your trailer.
Second, if filling the black tank directly through the toilet with a hose do I get the same result as filling with the flush line.
Third, what products, natural or chemical, do you use to try and clean the sensors. I Ued CLR in my last TT and it seemed to work. Not so much on my 5ers.
Sorry for the long post, but I feel a stupid question is better than a stupid mistake.

The flush feature uses a spray inside the tank, not just standing water. It works well. I do it 3 or 4 times when I prepare for departure and am amazed at how much more stuff comes out each time. Do not leave the running water unattended though.

[Graham]

We head south in the winter and move around a lot so the action in the tanks keeps them quite clean. Sensors are of little value. Where I've had a problem is setting it up back home in Canada in the summer for 4 months....the 'hill of poop' is a force to be reckoned with! I've tried the built in flush system and the flexible hose down the toilet with a spinning end. They work OK unless you've let the pile get too big and too 'solid'. My answer was to attach a 4 inch closing valve on the outside that has a water hose attachment. Hook your hose up to it and put back flow into the black water tank (be sure to close off the grey water tanks). This will break up the blockage. The attachment is clear so you can turn the water on & off then open the valve to see when the blockage was released. I then follow up with a good flush with the units built in system. Good Luck!
btw....I noticed not many people hace said they use the tank additive...I feel they are a wase of money. I also question the ice cube trick. Unless you drop a lot in just before you are ready to move I feel they would have melted before they have ay real effect....although I haven't actually tried it

[40 Cal. Mark]

Been full time since Feburary '17 We bought a 17 3721 RL and grey and black tank sensors kinda worked 1st week but have read full since. All methods suggested will work but the commando treatment works well. We use that when we are ready for our next adventure. Also clear 90 degree elbow helps

[richfaa]

I do not know what one has to do to get the "poop pile". We are long timers and live in this thing most of the year.We have never had a "problem" with back up in the black tank.

We are most always at full hook ups. There are just the two of us .We flush every 4 days or so.We use our bathroom the same as we do at home that is we use a lot of water. We are at a full hook up why restrict water usage . It takes 15/ 20 may be even 1/2 hour out of our busy retired day to flush ALL the tanks.We have a clear elbow at the flush output so we can see what is coming out. No the tank sensors do not work for long we have had 6 RV,s and none of them worked for long. We do not need tank sensors to tell us when 4 days have gone by and it is time to flush the tanks.

Rondo in post #14 has a very good procedure It will work.

[Rcerne]

I've found the King Flusher works great back flushing the tank. I've attached a GPM water monitor you can pick up at any garden store or find it on Amazon for a few dollars. That way you can keep track of the amount of water you are putting in your tank. I put 40 gallons then flush tank. I do it 3 or 4 times until water runs clear. You can watch a video on YouTube that shows it is by far the best way to clean your tank. Nothing gets it as clean as new but this comes close. My black tank holds 55 gallons so I cut the water off and flush when it gets to 40. Better safe than sorry! Plus close your grey tank valve or valves, depending how many you have, when using the King Flusher. You don't want black water flowing back in grey tanks. I've also used it on Galley Tank to get food particulates flushed out.