Wednesday, November 12, 2014

For the First Time...

This will probably be one of the shortest articles I have ever written for this site. For the first time since we got the Roadtrek, my black tank sensor reads empty. This may not sound like a big deal to most but to RV owners this is a rare occurrence. At the time that I am writing this article it has read empty for three weeks now.

I have written before that we have tried the GEO method of treating the black tank. This is the mixture of Calgon water softener mixed with washing machine liquid detergent. We did this for a year it had no better result in keeping the waste flowing out of the tank and keeping odors down than just using the tank chemical - digester/deodorizer/lube - that we buy in Walmart's RV section and have used since we first got the Roadtrek. Toward the end of that year of trying this I started adding the tank chemical to the GEO mixture to see if that would improve the result. The result I was looking for was to see the black tank sensor go to Empty - the bottom LED. That never happened. I tried cleaning the tank by flushing it with water through a tank wand. I tried pouring ten gallons of clean water down the toilet into the black tank after dumping and dumping again. No change. The sensor would read 1/3 or 2/3 and as soon as we started using the toilet the sensor would read Full. Sometimes each press of the test button with the empty tank would change from 2/3 to 1/3 and back again to 2/3. We knew the tank was empty but the sensor didn't. I pretty much gave up and at the end of the 2013 season, took the bottle of Calgon and the bottle of laundry detergent out of the Roadtrek and stored them away in the basement. Meryl does not use this type of laundry detergent in the washer at home and we don't need to use Calgon so they have been sitting there since last year.

Here is how I achieved the black tank sensor reading empty - and I hesitate to put this out in case it is a fluke and one time thing. And should it turn out to be that, I will come back to this article and let you know that it was a failed hope.  So, before our last trip I saw the bottle of Calgon in the basement and decided that since it was just sitting there, I would try an experiment. Since the trip before the tank sensor was now alternating reading Full or 2/3. It had never read full after dumping before.  I took the Calgon out to the Roadtrek and filled the entire bottle cap with liquid Calgon water softener. This is about three times what is recommended in the GEO method to do. I flushed it down the toilet into the black tank and followed it with a little water to get it out of the drain pipe and into the tank. There already was our usual one gallon of clean water added to the tank after dumping and the usual two ounces of the tank chemical treatment. That was it.

We went on our next trip a week later. When we dumped the black tank and the grey tank, I took the garden hose that we carry for the tank wand, connected it to the campsite water spigot, and added a shut off valve to the end of the hose. I shut the Roadtrek water pump off as I did not want that water going into the tank at the same time.  The hose was snaked into the Roadtrek through the driver's door to the toilet. Meryl turned on the spigot and I pointed the end of the hose into the toilet with my foot on the pedal to hold the flap open and I turned on the water - full force pointing down the drain pipe into the black tank. It took a little while for the tank to fill and for me to see the water coming up the pipe toward the bowl (using my flashlight and "no drop" lanyard). I turned the valve on the hose to off and called for Meryl to shut off the water. The hose and I then went back outside. We dumped the black tank again. The water that flowed was fairly clear.  I went inside and could not believe what I saw when I pushed the test button on the monitor. It read empty. It then went to 1/3 and I thought it was worth a try.

During that day we were traveling around the area before heading home that night and I checked the tank sensor again at the first stop. The black tank read EMPTY. And it has stayed that way to now (now being when this article was written which is not the day it is published). Was it the Calgon or the hose? Since I have done both before but never as much Calgon as this, I think it was a combination of too much Calgon - a full cap - and the heavy rinse with the hose to a full tank.

We have another trip coming up - again, before this article will appear - and I will repeat this. This next trip will be the last trip of the season before winterizing and I want that black tank empty for winterizing after this trip. If it works again, I will be back and share what happens in an addendum on this article. Stay tuned for the end of this cliffhanger.


A week before our next trip I went in and put another full cap of Calgon into the black tank. Before I did I noticed that the black tank monitor was no longer reading empty but now was at the 1/3 LED. When we started using the tank the first night of trip the monitor went quickly up to 2/3 and was at Full by the start of the next day. The tank was far, far from full. At the end of the the trip I flushed and emptied the tank and the monitor went no lower than 2/3. Back to the same old reading and it did not go down to 1/3 as it had been. When we winterized - and the tank was definitely empty - the tank was still at 2/3 and will likely stay there until the Spring. SO - it was nice while it lasted but perhaps this was a one time thing, not to be seen again. I did purchase another bottle of Calgon and it will be used through the new RVing season when it comes> We shall see if we ever get to see the monitor say the black tank is empty again. Until then don't jump to try this.   At least I can say now that I once saw the black tank monitor read empty.


  1. A sighting of an empty black tank indicator is like a sighting of Bigfoot !

    1. That is very true. When you see it you look twice and then still doubt what you saw. And you will likely never see it again!

    2. Is your 190 still under warranty ? What does Roadtrek say ? You can install "after market" sensors on the black tank which I have seen on you tube and seem simple enough to install providing you have the use of a lift for the van itself. Given your purchase of Calgon it's probably worth it since I can tell you want accurate sensors.

    3. I had dealer service look during the first year. They decided to remove two sensors from the black tank - under warranty - and replace them with new sensors which they felt should be positioned differently to get correct readings. They had to take down the black tank to install the new sensors and because the old sensors can't be removed as they would leave a hole that cannot be patched, they were left in place and the wire leads were moved from the old sensors to the new. They also replaced my monitor panel when new as it had bad LEDs that would not light also under warranty. It is the nature of this type of sensor system to give false black tank readings. The only sensor system I have read positive reports on is the SeeLevel sensor system which goes on the OUTSIDE of the tank. If it is possible to install that someday I may have that installed - but it means a different monitoring panel as well and I am not sure that it will accommodate the dual fresh water tanks in a 190.

  2. It would be nice to have accurate sensors for the black tank. We know how to tell it is full by looking down the toilet - where my flashlight lanyard comes in handy - and how to gauge usage - about four days to fill it, but if I have to dump before it is full I am filling it with water to be sure we are over the 2/3 recommended before dumping the tank. It sure would be nice to look at the panel and see 2/3 and know that it really is 2/3. Heck sometimes I put 7 gallons of water or more just so we can dump the tanks.