black tank

2018 2400, dumped black tank using macerator, valve wouldn't close all the way, looked through the toilet, bottom covered with sludge. Opened 3 inch manual dump and flushed it clean. Black tank valve then closed. Do I have to flush every time? Seems when using macerator all the liquid drains first leaving sludge behind in the tank. Why do I need electric dump valves? Using a manual valve   is fool proof.

  Lynn

Lynn,

I have had no issues with the valves or macerator on our rig.  I think the reason for the electric valves is because the valve itself is under the rig and not easy to get to.  On my 2552 anyway, maybe not on your rig.

Standard recommendation is to not dump the black tank unless it is 3/4 full.  And to put back about 5 gallon of water after dumping so the bottom of the tank stays "sloshy".  I only flush the tanks occasionally.  Twice last year, not because of any issues, just wanted to try out the flush system.  Seemed to work.

Jatrax, I think you are correct on why PC uses electric valves. My black valve is easy to reach, my gray valve is under the coach. My black tank is rated 23 gallons, when empty it wouldn't hold 18 gal of water. I think they use outside measurements of the tank to figure capacity, it still should be closer than that.

  Lynn

Hi Lynn. . .we also have a 2400, but ours is on a Sprinter chassis and the black/gray tank sizes are reversed for us (23 gray/35 black). The best results are to not be too cautious with flush water. . .the more the better.  That being said, with your smaller black tank, water use has to be less than what we use.  Try traveling with about 2-3 gallons of plain water (or liquid contents) from location to location.  This will help break up solids with the sloshing effect.

We have posted this in other threads, but we have found that a proper ratio of plain water to black tank contents acts as a natural deodorizer and solids breakdown agent.  This concept has been verified by at least two septic tank professionals as well as a bunch of our full time RV friends and our own personal experience.  We have never used any black tank additives after the ones that came with our first travel trailer.  Both of us find most chemicals to have an offensive, sickly sweet odor.

Our macerator seems to like what we do, and I back wash both tanks every 2-3 full hookups.  Happy trails. . .

2018 2400, dumped black tank using macerator, valve wouldn't close all the way, looked through the toilet, bottom covered with sludge. Opened 3 inch manual dump and flushed it clean. Black tank valve then closed. Do I have to flush every time? Seems when using macerator all the liquid drains first leaving sludge behind in the tank. Why do I need electric dump valves? Using a manual valve   is fool proof.

  Lynn

Just curious, how did you know the electric valve wouldn’t close all the way?

 The gears were slipping making a funny noise and the light was still blinking. After I flushed out the tank it worked fine. I wonder if a foreign object could have been in the tank?

  Lynn

Possible.  One thing we noticed was that there were a lot of plastic shavings in our fresh water tank.  I've read on other forums of people finding plastic cutouts or parts in the tanks or plumbing. 

After we flushed everything out I have not seen any addition plastic.  I remember in our sticks and bricks house the same thing happened.  Had a faucet clog up and when I took it apart there were plastic pieces inside the lines.  Just new construction debris I guess.

Hopefully anything that was there has flushed out now and you will have no further issues.

When I opened the fresh water door there were plastic shavings in it, I suck them out with the vacuum then filled the tank. I thought later I should have unhooked the fill hose going into the tank and flushed it out, if any shavings were in there they washed  into the tank.

  Lynn

Would back-washing (also called blending) the gray water into the black tank the night prior help flush out the sludge?  We have discussed blending the tanks to increase gray water capacity on another thread, but maybe doing so will also help flush out the black tank when it comes time.

You might want to consider using an adapter to back-flush your tanks.  I believe the use of one has helped in emptying/cleaning our gray and black tanks.  Also agree with others about keeping some water in both tanks. 

2018 2400, dumped black tank using macerator, valve wouldn't close all the way, looked through the toilet, bottom covered with sludge. Opened 3 inch manual dump and flushed it clean. Black tank valve then closed. Do I have to flush every time? Seems when using macerator all the liquid drains first leaving sludge behind in the tank. Why do I need electric dump valves? Using a manual valve   is fool proof.

  Lynn

I personally like to dump the standard manual valve. The secret is to have full tanks so the pressure cleans the tanks better than the macerator. I am a widow and travel by myself and it takes awhile  to fill the tanks.  So I will fill them with the water and watch the gauge and them dump.  My late husband told me about that as he was in the RV industries.  You need force to do a good cleaning dump.  Just a suggestion.