Black tank help!!!

If you don't have the valve closed and haven't put in 3-5 gal. of water before using the toilet (after each dump), liquid will flow out right away while the solids stay there and builds up the RV-ers infamous "pyramid of poop". The pyramid can still form sometimes even if you have the valve closed and don't add the 3-5 gal. before use and use adequate water each time you flush. RV holding tanks aren't very deep and it doesn't take long for a pyramid to build up .

A back-flush elbow that connects to the outside sewer outlet may or may not work depending on the shape of the particular tank and where the outlet pipe is connected on the tank. An in-tank wand may work as an alternative and they don't cost much. If the toilet drops straight down into the tank, you could try breaking up the pyramid with a stick.

If you can get a rubber hose, cut the hose leaving about about 8' or so of it. Connect that to another hose, push it into the tank through the toilet and turn the water on full (valve open). Repeat as many times as you think are necessary to make an effect and each time, pull the hose out and try and point it in another direction. Not sure where you are parked, but you can also poke the hose up the outlet pipe but need to be prepared for some "stuff" to come out onto the ground. We had a badly plugged tank in the beginning and the CG host gave us a piece of rubber hose left by another camper and showed us how to use it. We still have that piece of hose laying on the ground at home but ever since we learned to use adequate water, have not needed it again.

You can use Liquid Drano along with some water. It won't harm plastic or metal - our KZ owner's manual says to use it. We use it once or twice a year to clean the tank sensors off. You would normally drive around for a while to make the liquid slosh around and if stationary may need to repeat the process a few times. I have sometimes wondered if an orbital sander (without sandpaper of course) held under a tank would help disperse the solids. Some do that with a home workshop size of sandblasting pot to prevent the media from clogging.

Some insist you must use an RV chemical before each use of the tank and some insist you need nothing. Chemicals will never be in a tank long enough to break down anything and I don't believe in them. Always fill the tank to near full before dumping and also do a good flushing after each dump. Sometimes filling the tank up again once or twice will help to get remaining stuff to move out.

When you do get this taken care of - no chemical are necessary. This is a holding tank, not a sewer system. All you need to do is keep the valve closed and use generous amounts of water if solids are present when you flush. We have been full-time for 7 years and have never used chemicals and have never had a problem. There is no odor when water is used either as long as the seal is good on the toilet and you put a small amount of water in toilet after you flush.

Fill five gallon bucket with HOT water and pour down stool with valve open. Pour as fast as it will allow and repeat with several buckets of HOT water.

HOT WATER will break down solids faster and the force of the large volume will help.