Black tank indicator - RV-Dreams Community Forum

granny · RV-Dreams Family Member

Black tank indicator

NorCal Dan · RV-Dreams Family Member

Sounds like you need to flush the tank better. "Stuff" sticks on the walls, then when the tank is emptied, there is nothing to hold the "stuff" up and it slides slowly down the wall. If it hits a sensor you will get a false reading.

FWIW, I wouldn't waste money on the cleaner/enzyme stuff.

Waggin Tails · RV-Dreams Family Member

Most here will tell you the key to draining is lots of water. We have a back flush for our black tank. The only times we've been down to one light (empty) is after serious back flushing.

First, make sure you have a clear elbow on the discharge line so you can see what is coming out.
Then open your black tank and confirm that there is little or no flow.
If you have a built in back flush for the black tank, now would be the time to connect a hose to it. I use a pressure regulator here so I do not over pressure any fittings. With back flush water flowing into the black tank, you should see increase in water flow at the clear elbow.
If you do not have a built in back flush, you could use something like this http://www.pplmotorhomes.com/parts/rv-toilets-tanks/holding-tank-rinsers.htm. The idea is to get water flowing into the blank tank while observing increased flow at the clear elbow.

No increased discharge would indicate something is not happy. Some of those clear elbow have a place for connecting a garden hose that will allow you to spray water back into the tank from the discharge point. If somehting is hung at the gate valve, this should clear it.

Sorry this was lenghty. Hope this helps.

PS -I also agree with NorCal Dan.

-- Edited by Waggin Tails on Tuesday 22nd of November 2011 09:33:48 PM

DorisandDave · RV-Dreams Family Member

I will also close the black tank valve while using the flush for a couple of minutes and then open and close the valve a couple of times to free anything that may be stuck at the valve. Just don't walk away from the valve if you close it while flushing. Rarely have I gotten the read out down to show empty after dumping. Normally it will show 1/3rd and then a couple days later 2/3rd. I will usually dump my tank after about 7 to 8 days.

I was told by DRV that a owner of a MS would dump their tank, fill it about 1/2 full with water and add some liquid laundry detergent when traveling and let the sloshing clean the tank. Have not tried that one yet.

Racerguy · RV-Dreams Family Member

You will learn to know the different sound when you flush your toilet.It kinda burps and you then know it's time to empty the tank.Then a good backflush like described above will clean the tank.I agree on the additives,just use lots of water.

The Bear II · RV-Dreams Family Member

Racerguy is on the money.... The sensors are inaccurate. Your ears will tell you when it's time.

When it's just the two of us, I usually dump the black tank once a week or before travelling to our next destination.

Once dumped, I will add two gallons of water plus toilet chemicals to slosh around while driving.

NorCal Dan · RV-Dreams Family Member

Here's a link to an article I wrote in my blog about this problem. I still use this method with a slight modification. I do not use chemicals on a regular basis, but I do use Thetford Level Gauge Cleaner when we move to a new location. I fill both holding tanks about 1/3 full and then add the Thetford chemicals to the holding tanks. As we drive down the road the sloshing in the tanks will get them clean. I usually dump the tanks as soon as we reach our first overnight location with hookups. We normally move twice a year as we go from one workamper job to the next and this cleaning method has worked for us.

As others have mentioned, you will learn to manage your holding tanks the longer you use them. The black tank will burp when you flush the toilet. For the gray we normally leave the valve open as we do laundry almost every day and I don't want to worry about the tank level. If you decide to do this as well, I recommend you fashion a p-trap in your stinky-slinky to prevent odors from entering your coach via the sewer hose. I use a hose ladder to hold my stinky-slinky off the ground, so where the hose exits the coach water compartment I let the hose droop towards the ground before it rises up into the ladder. Makes a convenient p-trap setup. Since I only dump the black tank once a week, before I pull the handle I re-position the stinky-slinky into the ladder as the weight/force of emptying the back tank could damage the hose otherwise. The Rhinoflex stinky-slinky sewer hose works perfect for my setup.

Trabuco · RV-Dreams Family Member

Dan - I like your idea of the p-trap. Never thought of that, will use it in the future.

Mike n Angie · RV-Dreams Community Member

Guys & Gals,

Not to push some one product but on "youtube" is a video done by someone named RVGEEK. He has made several videos but the one on cleaning your black tank is GREAT!!!! We tried his cleaning method and were ASTOUNDED at the amount of material coming out of the tank when we thought it was clean! Take a look and try his method......it works and you have a-no-question-ask, clean tank. Let me hear what you think.

Blessings to all!