[dutchmensport]

There's only one reason why your tanks smells. It's because it's not flushed out and "stuff" is still hanging on. (Literally). Your tank need a good cleaning, and the only way to do that is to flush it.

Ideally, you should drain your black tank completely. Then add about 5 gallons of water, some Dawn Dishwashing Liquid or any kind of laundry detergent and then take the camper on the road for a while. When you reach your destination, dump the tank. The sloshing when driving will clean things up. A little bit of bleach goes a LONG way in getting rid of smells. Just be sure to flush the bleach water as soon as you can from the tank.

Another trick you can do, which is what I do every time I dump my black tank, and that is to back flush the grey tank water into the black tank. This only works if your black and gray tank outlets discharge through the same outlet. You need to attach a 3rd valve on the outlet, like a Flush King. The process is simple. Drain the black tank until it quits running. Close the Flush King valve and now open the grey water valve. This causes the grey water to flush backwards into the black tank. The backward flow of the water will help break down anything still "hanging on." When the two tanks equalize, close the grey water tank valve, and now open the Flush King again and drain the black again. You can repeat this 3 or 4 times depending upon how much grey water you have in your tank. Like I said, I do this EVERY time I dump my black tank.

Another thing you can do to help clean the tank out, is to catch your dish washing water in a pan. And rather than dumping it down the sink, dump it down the toilet. The soap water will help clean things up a lot more, and also reduce smells.

I never use any kind of RV chemicals in any of my tanks. Back flushing works about 90% of the time. For the other 10%, I always add about 5 gallons when traveling. Once a year, I may add bleach and go for that drive between campsites. And no, doing all of this, I never have to use the built in black tank flusher. Also, my sensors always work, and I almost never have smells. When we notice "the" smell, we add dishwashing water. We also have a washing machine that drains into the gray tank. The laundry soap back flushing also keep the tank odor free. And actually.... thinking about it ... since we got the washing machine (over 1 year now) ... um ... we've not had any black tank smells at all! The back flushing with the Laundry water is doing pretty darn good.

No RV black tank chemicals. Save your money.