Plan to clean black tank level sensors ??

[dmason]

Ever since we bought our coach (used, but new to us) the sensors in the black tank have not registered correctly, always showing at least 2/3 full even right after dumping. I assume this is because they are internal to the tank and have dried debris stuck on them.
We're hitting the road this weekend for about a 150 mile (one way) trip to a CG in Delaware. My plan is to fill up the black tank, thru the commode, to about 3/4 full with the hose and then let the water slosh around while we're on the road and then do a complete flush and dump once we get hooked up at the CG.
Besides water, is there something I should put in the tank to help dislodge/dissolve the debris? I've heard of Dawn and ice cubes. Your thoughts?

[94-Newmar]

See this article on the forums...
The Geo Method / Black and Gray Water Holding Tank Maintenance

[idenphones]

I did the Dawn routine, then the ice cubes, then I bought a $13.00 wand to wash things down from up above.

That worked the best!

But, the problem came back a week or so later. Seems to be an ongoing problem for allot of us.

I have found that by keeping about 1/3 of the tank filled with just plain water after I spray using the wand that the readings become reasonably accurate.

Trust me, you will know when the tank gets full! It usually takes a long time unless you have lots of visitors or drink too much beer!!

[InPursuit]

I've given up on the sensors.

I put a 3M post it note on the control board with the date of last flush.
So far so good. But the gray needs emtying far sooner than the black.

I doubt I'll do it but I've considered installing some sort of mechanical level detector. I have experience with the coffee urn sightglass type (Tomlinson).

But it would get just as crud encumbered as anything else.

No answers... just observations.

[bullydogs1]

Get some Calgon water softener as per the GEO methods....mix it into a gallon of water real well and dump into the tank...It keeps slings slippery inside the tank. will also clean the probes.

[Rocky Larson]

When you finally give up on all those methods, BTDT, you might want to try these. If you are lucky they are an easy install in your OEM sensor holes. Mine took a little over two hours to drill new holes and install. That included getting the drill and accessing and replacing everthing. Now when the tanks are empty they read empty and when they are full, well I still might have a day or two to get to a dump. After 5 years it's nice to see the 1/3 and 2/3 lights working as they should.

RV Holding Tank Sensors - Get accurate grey and black holding tank monitor readings

[Mike Canter]

If these are resistance sensors mounted through the wall of the tank then after a lot of hard work the only way I founf to clean them to make them work was to cut a hole on the opposite side of the tank for installing a tank flush system. Before I installed the tank flush I stuck the wand off a pressure washer through the hole and blasted the inside of the tank. It worked and it cleaned the sensors and the tank flush system worked and kept them clean from then on.

[Batman_777]

I think my Black tank may have external stick on sensor pads. If so, there are no holes or sensor posts or probes inside the black tank. The sensor pads use Mirus detector cells. I replaced the Full sensor pad for the Tecma Power Flush Toilet opposite on the black tank side of the MH. We have one gravity flush toilet and one power macerator toilet. There are many things that can give the sensors a false reading. RF interference being one of them. Loose connection another issue

http://www.touchsensor.com/pdfs/1803_SensaTankRV_3.pdf

http://www.sealandsanitation.com/Sen...on%20sheet.pdf

I kept getting false readings from the Full Pad. I replaced it and moved it around, and placed aluminum duct tape over to help eliminate RF interference (Hmmmm I could have made an antenna). No matter, Nothing worked. So I ended up with it just loose from the tank. Now it always reads Zero.

[Bobs911]

The "Geo Method" works about 95% for me. Kinda hard to find the water softener here, but I see it now and then and grab a few boxes. One thing that seems to make a difference is I put at least 5 gallons of water in with my wash bucket after I dump. My grey is always full before black, so the 5 gallons doesn't hurt my capacity. Also, if I have the opportunity, I'll fill my black tank through the flush/rinse fitting and immediately dump just to rinse it out.

[InPursuit]

Quote:

Originally Posted by Mike Canter If these are resistance sensors mounted through the wall of the tank then after a lot of hard work the only way I founf to clean them to make them work was to cut a hole on the opposite side of the tank for installing a tank flush system.

This is an intriguing idea.

I'm thinking of a fitting used in the bowls of commercial garbage disposals to introduce water there. 1/2" IPS with a nice chrome plated finish. Add a solenoid valve and a relay and a control (even a timer) and it could flush the probes as desired.

The problem of course is getting the fitting *inside* the ABS tank.

[itdave]

Sealevel sells an external sensor system that will integrate with your Aladdin system. Mine does not integrate but I installed the SeaLevel 4 years ago and have never had a incorrect reading since.

[ShapeShifter]

I use one of these wands with the rotating spray head once or twice a year, and it does a very good job of removing the accumulated gunk. The regular in-tank "No-Fuss Flush" that came installed by the factory does a good job keeping it mostly clean, but needs a little help from time to time.