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Old 12-09-2019, 03:13 PM   #1
Jeremy888
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Black tank problem

I have mentioned before that the previous owner apparently left a huge mountain of poop in this 2016 3950 BR Montana 5er. For 3 years now I have been working on getting it gone ,hopefully also to get my black tank monitors to work ..They always show full. I recently purchased a new product that has been eroding that mountain down .It is pictured in the photos. Note that I am still getting old toilet paper out of the tank after putting none in for 3 years so I know this product is effectively helping .

I have several questions about the construction of the drain system .This 5er has 3 tanks ,1 black 2 gray. Looking at the photos shown you can where the black and 1 gray tank come out of the tank or tank peremiter ( there is an I beam from the front of the rig behind which apparently hide the tanks and actual valves ) A 3" ABS comes aft into the 3 "ABS pipe running to the left side that connects to the discharge hose . The after end of the I beam can be seen in that same photo . In another photo you can see where the forward 2" kitchen ABS line joins the same 3" line to the hose. Also note the 2 valves for the fwd tanks are minimum of 5 feet from the same 3" discharge ABS. I have determined the forward gray tank is forward of the black tank by previous tests and the vents. Note that the forward gray tank valve us aft of the Black tank valve. Obviously the valve system is also inside this I-Beam or tank peremiter ? Today I noted several things that I found odd that leads me to ask how the system is constructed. What I was doing was filling the tank with the flush water for about 2 minutes , I have determined I can fill the 49 gallon black tank in about 3 minutes . So it is about 2/3 full in 2 minutes . What I observed to day was that after filling about 2 minutes and then opening the valve it took 75 to 85 seconds before a solid pipe full of water was observed exiting the pipe. It came out before 75-85 secs at an increasing rate til it finally filled the tube. Then a plug of poop and paper or 2 would exit and then it would start burping with air pockets and slow down to the flush water rate . Why does it take so long ? If I fill it for almost 3 minutes ,as soon as I pull the valve it comes out solid . It seems to me that if it comes out solid 80 seconds after it starts that the mouth of the valve or the tank end of the drain pipe has to be below the level of the water and the slow rate prior to full flow is due to the plugs from poop mountain .I was amazed at how many toilet paper plugs came out in the 2 hours I filled and flushed.

Questions:
Can anyone tell me why it takes so long at 2/3 full ?
Any one have a construction diagram of this,sysyem or can describe it.

If I understand how it is constructed it may help me solve the problem .

Anyone observed similar symptoms?

All input gladly accepted m
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Old 12-09-2019, 08:30 PM   #2
bobbecky
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Our rig is obviously different from yours, but our black and grey tanks are mounted along side each other and out of the rear of each tank is a drain valve. From each drain valve is a 90 degree elbow turning toward each other and meets up with a wye fitting where the two lines connect to and from the wye fitting the three inch line exits the belly area and turns toward the left side of the rig. Our galley tank is mounted aft of the axles and the two inch line from that tank connects to that three inch line going to the left side of the rig. We don't have a washer installed, but that line connects to the three inch line after the two tanks, black and grey so if draining requires no valve operation so must be connected to a drain directly. Hope this helps.
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Old 12-10-2019, 05:29 AM   #3
Archergodwin
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Maybe double check your vent line? Almost sounds like you have an 'air lock' situation that perhaps a 'full' tank overrides easily, but a 2/3 full tank does not.
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Old 12-10-2019, 05:55 AM   #4
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Thanks bobbecky and Archergodwin for the comebacks. I noticed there is large plastic sheet, attached with screws to the beams hifing my system and I'm guessing that my system is similar to yours bobbecky...Im trying to avoid taking it off. So just because the grey vent is considerably farther forward than the black vent ,it does not necessarily mean they are not side by side. My assumption was they were not side by side. If mine is like yours it definitely accounts for the valve placements as they are. And if a large plug got situated just right at the 90 it could account for the delay in solid stream. I will run a hose down the vent again as per Archergodwin's input . His guess does account for the burping action ... Thanks to both of you.. I'll get back here after I have tried again .
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Old 12-10-2019, 10:30 AM   #5
flybouy
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What I was doing was filling the tank with the flush water for about 2 minutes , I have determined I can fill the 49 gallon black tank in about 3 minutes .
What are using to fill a 49 g tank in 3 min.? That's over 16 gal/min. or nearly 1 quart/second. You must have a fire hose on that connection. The maximum for 1/2" pipe is 14 gal/min and your lucky if you get half that.

Take a 5 gal bucket and time how long it takes to fill it. Divide that time by 5 and you will have your flow rate.

As for the slow drain rate it could be an obstruction (either at the tank/pipe connection, somewhere in the pipe, or in the valve) or the valve isn't opening all the way. If it "glugs, burps, or gurgles" then it's most likely not venting and the exit flow is interrupted while air enters thru the drain pipe (think turning a soda bottle or gallon jug full of liquid upside down).

In your posting of pictures you show a waste "digester". If you are using that for the "2 hours of Flushing" you're wasting the money using it. Waste digesters take time to work (think days if not weeks). I would use the "old school" wand thru the toilet valve where you can direct the stream to the poonami for the best results.
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Old 12-10-2019, 01:09 PM   #6
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Quote:
Originally Posted by flybouy View Post
Quote:
I have determined I can fill the 49 gallon black tank in about 3 minutes
What are using to fill a 49 g tank in 3 min.? That's over 16 gal/min. or nearly 1 quart/second. You must have a fire hose on that connection. The maximum for 1/2" pipe is 14 gal/min and your lucky if you get half that.
Unless he has a 30-gal poop mountain in there... he's been working on it for three years!
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Old 12-10-2019, 03:37 PM   #7
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Flybouy Thanks for the comeback , 3/4;" pipe ,80PSI fills 2 gallons in 8 seconds , 4 in 16 , 8 in 32 sec. rounded to 30 seconds for safety so 16 gallons in a minute times 3 minutes is 48 gallons. So at full pressure I can overflow it easily if I'm not careful. Today I dragged a hose up on the roof to check the vent . I left valve open and started slow so I wouldn't have a $hit storm in case it was plugged. No problem, if it was partially plugged it wasn't anymore, cranked it up to full pressure . Went down to watch the show. It was washing out moderate amounts of toilet paper and poop. I had flushed it 2 hours yesterday so this was definately erosion off poop mountain. I started the flush sysyem to help the vent water and did a few quick fills and dumps stopping the fill at a minute for the double flow rate . I still had a delay and burps at 2/3 of a tank but only about 40 seconds now rather than 80 . Full tank at 90 seconds produced instant full flush ,but still some burping towards the end . This leads me to believe that the installers shoved the ABS vent to far down into the tank .This fits the symptoms best . If that is the case I'm gonna live with it Now as far as wasting poop eater product...never happen . I''m Scots Irish , the Irish in me wants to drink ,but the Scots in me doesn't want to pay for it .

Lhaven , I certainly hope it's not a 30 gallon mountain , but it sure could have been when I started excavating it.. I'll keep chipping away at it . Water and water and more water is going to do the job over time.. Hope I don't get busted for wasting water down here in drought prone Southern Cal. Lovely weather but the rain and fresh air of
North West Washington always looks good after snow birding here 5 months. People here on the freeway are crazy and impatient , rarely using their blinkers, always using their horns and very handy at driving while texting with one hand and giving you the finger with the other . I drive the speed limit so I'm very unpopular ...

Any one else who wants to weigh in , Im appreilciative. Jeremy
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Old 12-10-2019, 08:18 PM   #8
bobbecky
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I have used tanktechsRV treatment for a long time and never have any issues with the black tank. This is a link to a video on their site that shows a simple device that can be made with a few simple parts that will break up a pyramid in your tank, and will do it quick. https://tanktechsrx.com/faqs/how-to-...unplug-a-tank/
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Old 12-22-2019, 09:33 AM   #9
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I know you are having an extream problem with your black tank. You mentioned The level always reads full. If your tank has the inside buttons that read the level you need to replace them. They are grounding out because of the poop resadue on the walls of the tank.
I replaced mine (all tanks) with the Following Valterra T21301VP Horst Miracle Probe - Black Water Tanks, Pack of 4, they also make the same for gray and fresh water tanks. Check on amazon.com. They work great.
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Old 12-22-2019, 10:16 AM   #10
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Have you dumped any hot water down the toilet itself into the black tank? Hot water can usually help poo dissolve faster than cold water. (Don’t ask how I know from our S&B house toilet...) Carry some buckets of hot water out from your house (or the campers shower), dump them in, let sit for a 1/2 hr or so, and then start flushing the tank normally like when dumping it. It will take more than just a bucket or two. You will want enough hot water in there to try to cover most of the poo mountain. And, not so hot it will melt anything plastic. Also, stick a hose down the toilet itself with the foot valve held open after the hot water treatment, that should dislodge even more while flushing.
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Old 12-22-2019, 10:46 AM   #11
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I don't have the patience to read the whole thread so sorry if this has been covered - When my sensors have been covered I have filled the tank to the top and let it sit for a few days and it always has fixed it. I think pieces of TP just get stuck on them and sitting under water dissolves it.

I can't imagine there is a 30 gallon pile of poop sitting in the tank and covering all 3 sensors but anything is possible, I guess.

As for cleaning the tank, a clear fitting to watch as you drain works great. Just keep dumping buckets of water in or fill a bit and drain until it runs clear.
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Old 12-22-2019, 11:00 AM   #12
61Hawks
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My brother in law had the same problem and we removed the chloroplast from under and put a garden hose down the toilet on full and I laid under the rv and beat on the center of the tank. After doing this for about 1 hour the "blockage" came rushing out fast and never a problem again. He did sit in the bathroom to make sure the toilet didn't overflow. Good luck
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Old 12-22-2019, 11:20 AM   #13
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Hydro flush

I bought a used 5er and had a similiar prob that was corrected by having a hydro flush of the tanks. I use Unique as well to maintain my tanks and sensors. The hydro flush in Sol Cal cost me bout $300.00 but was worth the time and frustration of flushing as you have stated. The hydro wand went up each pipe and the pressure cleaned the tanks ( since I have a clear 45 degree at the top of my flex line we were able to see it go from dark to clear in no timeL. When I relocate between sites I put in a gal of fabric softener and let the sloshing clean the tanks. Upon arrival at site a quick flush (also freshens the lines) and add unique to the black tank until the next flush.
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Old 12-23-2019, 06:02 AM   #14
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Originally Posted by 61Hawks View Post
He did sit in the bathroom to make sure the toilet didn't overflow. Good luck
Well! I hope he felt better. Sorry, I couldn’t help myself

While it will do nothing to a pyramid, the wands do work great for rinsing off the sides of the tank, including the sensors. Be careful when using it (if you do) because if you raise it up higher than the drop pipe you will get a splash right in the face! Definitely not recommended. At least keep your mouth closed.
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