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Black Tank only holds 1/2 to 1/3 of capacity

TexanSon
Explorer
Explorer
I recently (August) bought a used 2017 Catalina Coachman. Found out about a week later that the black tank valve had been left half open. Currently I am having to dump the tank about every two days (there are two of us in the trailer), and take a sprayer wand to it once a week, at least.

I'm looking for suggestions of products that might help with this situation, or cleaning techniques to get rid of residue that I'm pretty sure has been built up since before we bought the trailer.

It is supposed to have a 30 gallon black tank, but, after the last time I dumped the tank, I poured about 10 gallons of water in, and it was reading full again.
TexanSon
USA (Ret.)
25 REPLIES 25

ktmrfs
Explorer
Explorer
Vintage465 wrote:
Glad it looks like you're at the end of the issue. I've found a few things that affect black tank performance..........if you can call it that! 1st.....forget about the sensors, as mentioned, they're a sails pitch and will need constant cleaning from jet pressure to even be in the ball park. 2nd, make sure you figure out your "water to solids" ratio. Meaning make sure you're not concerned about conserving water that there is not enough water to help disolve/break-down solids and toilet paper. 3rd, make sure you're dumping on a reasonabley level or leaning to the dump side surface.


On the "water to solids". When we boondock, DW and I go about 7 days and the 32 gallon tank which uses the sealevel gauge system is about 50-60% full. Be careful with TP. the tank then get sloshed around till we either get home or to a dump station (usually home). Doing this it does require the use of the tank rinse system to clean the tank, but we've never had any other issues. Even with 4 adults and 2 grandkids we can go a week before filling the black tank.
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Vintage465
Nomad
Nomad
Glad it looks like you're at the end of the issue. I've found a few things that affect black tank performance..........if you can call it that! 1st.....forget about the sensors, as mentioned, they're a sails pitch and will need constant cleaning from jet pressure to even be in the ball park. 2nd, make sure you figure out your "water to solids" ratio. Meaning make sure you're not concerned about conserving water that there is not enough water to help disolve/break-down solids and toilet paper. 3rd, make sure you're dumping on a reasonabley level or leaning to the dump side surface.
V-465
2013 GMC 2500HD Duramax Denali. 2015 CreekSide 20fq w/450 watts solar and 465 amp/hour of batteries. Retired and living the dream!

TexanSon
Explorer
Explorer
Update, maybe final one for this thread.

First, thank you everybody for the advice. I've been using Unique in the tank for the last week. Dumped the tank last Friday, and then today, 5 days later. Based on limited visual inspection, the tank looks pretty good (for a black tank), and I think our problem, now, is just that we are slightly off kilter. I've got a few issues that I need to work out inside the trailer before I can even think about trying to get the level better, but I will definitely be high-siding the trailer when I can move it.

Again, thanks, everybody!
TexanSon
USA (Ret.)

ppine
Explorer II
Explorer II
The sensors are notoriously inefficient. Make sure you use TP made for RVs that breaks down quickly. The special devices for tanking rinsing work. Instruct your companions to minimize the use of TP.

TexanSon
Explorer
Explorer
Keeping an eye on that. Added Unique to the tank Tuesday, dumped the tank on Friday and added more. Going to add some more this morning, and hopefully not have to dump the tank until at least tomorrow.

Thanks for the advice!
TexanSon
USA (Ret.)

dave54
Explorer III
Explorer III
Like the others noted, the sensors never work right. I will flush and clean the tank, and after about the second flush the sensors all read full again.

I can tell how full it is by the smell when I flush. When I detect the tell-tale odor, it's about 3/4 full and time to plan a dump.
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Bionic_Man
Explorer
Explorer
Echoing the chorus of don’t trust the sensors. They are never accurate.

When I had the pyramid of poo I used rid-x.
2012 RAM 3500 Laramie Longhorn DRW CC 4x4 Max Tow, Cummins HO, 60 gallon RDS aux fuel tank, Reese 18k Elite hitch
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msmith1_wa
Explorer
Explorer
Typically there are three sensors on the holding tanks.They are typically spaced at 1/4, 1/2, and 3/4 of the height/depth of the tank. Monitor panels are typically labeled 1/3, 2/3, and full. With this setup when the monitor panel shows full the tank is actually 3/4 full. Or leaving 1/4 of the capacity remaining.
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midnightsadie
Explorer II
Explorer II
never trust the sensor there wrong from new not a good way to check your problem. pull the commode and get a good light . might pay to pull the tank and clean.

rhagfo
Explorer III
Explorer III
schlep1967 wrote:
Go watch this video National RV Training academy. I would go with the liquify brand based on his test.
In your situation it may take a few treatments to get it cleaned out.


I was in your situation, but not full time used about 1/2 box of Rid-x added about 10 gallons of warm water and let it sit for a month.
In your case I would use a heavy dose of either of the two products listed. Go as long as you can before dumping, the use a wand to help clear out the residues.
Russ & Paula the Beagle Belle.
2016 Ram Laramie 3500 Aisin DRW 4X4 Long bed.
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mosseater
Explorer
Explorer
If there is liquid just below the flush ball looking down into the toilet, at least you know it's full. Do not trust the lights. They are almost universally wrong. Turn the pump off, open the flush valve and see what you can see first.
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valhalla360
Nomad III
Nomad III
Check out YouTube...the ice trick doesn't do anything.

If on a full hookup site try leaving the valve open with a hose running down the toilet for an hour or so....just keep an eye on it in case something large breaks free and clogs the outlet.
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Oregun
Nomad
Nomad
You could buy/rent a flexible inspection camera and put in the tank through the flush valve in the toilet with the water turned off and take a look inside the tank to see what you are dealing with. Also look for crud buildup on the sensors in the tank level indicators.

TexanSon
Explorer
Explorer
I don't think my tank is a straight drop tank, opnspaces. But, no, I haven't seen any build up directly below the toilet.
TexanSon
USA (Ret.)