Good Black flush "trick" or bad idea?

[TNGW1500SE]

When dumping my tanks, I've got a new "trick". I drain the black water first and let the hose and tank empty out. Then I leave the black valve open, hold the sewer hose up (above the level of the tanks) and open the grey valve. This lets the grey water rush into the black tank. Before the grey water stops rushing into the black tank, I close the grey valve and lower the hose, thus emptying the black tank again. I'm able to do this "flush" 3 or more times depending on the grey tank level. I leave some grey water for the final hose rinse. I'd estimate I use 5 to 8 gallons of grey each time I do this "flush". I'm careful not to let the tanks equalize allowing black water to the grey tank. I can tell when the greys running low because the gushing (from tank to tank) slows down. It seems to really help clean the black tank. I've got one of those clear fittings so I can see the color of the water. The first time I do it, the water is nasty brown but after a couple of cycles it looks like "clean", soapy grey water. I wish I had a third valve where the hose is connected but there's no room to install one so I just hold the hose up to stop the water flowing to the sewer. Soooooo,,,,, is it a good "trick" or a bad idea?

[DSDP_Don]

"TNGW1500SE".....One thing that was never mentioned and some people don't know.....you're 3" drain, where you connect the sewer hose is designed to rotate. Typically, it's rotated down so that the hose can be brought up through the bottom of the water bay. You can rotate it up, install the drain, (it has bayonet fittings) and come out your bay door with your hose when doing a final drain.

You can also add a clear extension to it and then attach it to your drain. There are many ways to get one to fit. You just need to take a good look.

[DSDP_Don]

"doublev".....The sensors in your grey tank are the same as the ones in your black tank. So your saying that your grey tank sensors have never worked, if the soapy water caused issues with your black tank sensors in one month. I think you might have another issue.

[doublev]

bigred1cav wrote:
Please explain, for we novice, how to use the valve to flush black tank?

rv2go wrote:

TNGW1500SE wrote:
When dumping my tanks, I've got a new "trick".

I don't like your "trick" I find it a lot safer using this.

Also when dry camping, I can divert gray water into the Black tank. Thus extending my stay several days as the Black tank seldom fills.

That valve goes right to the sewer hose. So to drain black you would need to open your black and then open that valve in the picture.

If you wanted to mix your tanks you would close that valve and open your grey and black.

To flush black you would drain your black completely, hopefully have a full grey, then close that valve, open both black/grey and (assuming black and grey were same capacity) half of your grey goes into the black tank. Now you have some nice soapy water in your black tank.

This has plus and minus.. plus is soapy water would clean better.. minus is that the soap residue can get on the sensors.

I tried this method and found my sensors are now off. I saw no benefit doing it. But give it a try if you have some issue with odors and black tank that cannot get clean and needs to be.

[bigred1cav]

Please explain, for we novice, how to use the valve to flush black tank?

rv2go wrote:

TNGW1500SE wrote:
When dumping my tanks, I've got a new "trick".

I don't like your "trick" I find it a lot safer using this.

Also when dry camping, I can divert gray water into the Black tank. Thus extending my stay several days as the Black tank seldom fills.

[tomman58]

Boy all this chat really seems way over the edge. We never have gone through this stuff. Use the back flush in the black and generally at the RV park we just leave the gray open then a day before the black dump close the gray and let it fill up, drain done.
We don't leave the gray open in RV sites that we do not know or any of those in Texas huge cockroaches there.

[Rice]

I've noticed, when draining gray water into a bucket, that the first gallon or two is extra gross. So I open the gray valve and drain a couple of gallons first. That gets rid of the extra-grody gray water, and also lets me check to make sure everything's hooked up okay before dumping black.

Then when I back-flush with gray (using the pick-up-the-hose method), I'm not using the grossest of gray water.

[doublev]

This technique is recommended when you purchase a sanicon macerator pump. It is sold as one the benefits. I thought it was a great idea (as the manual says and i will paraphrase "flushing your black tank with soapy grey water is much better than flushing with regular clean water."

The problem is....

The soapy suds will mess with your sensors in the tank (at least they do with my thetford!)

So now I am dealing with a black tank with soap residue that is throwing my sensor off. This all happened when i started this technique about a month ago

[time2roll]

TNGW1500SE wrote:
hold the sewer hose up (above the level of the tanks) and open the grey valve.

All you need a hose spreader and a Y coupling to finish the shot :B

[427435]

If there's no lineup at the dump station, I put my levelers down on the side opposite the drain. That tilts the tank towards the drain and should help things slide out. It's a lot safer than what the OP is doing. That, and the GEO method, has kept any odor problems from developing.

[AllegroD]

Get a valve. Much less chance of a spillage disaster.

[dcbrewer]

Why not add a black tank flush kit, Ijust hook the water hose to mine and can hear it spraying the inside of the tank, and let it run till the water comes out clear. Just don't forget it on with the main valve closed or you could have a mess.

[hughesjm21]

Seems like a simpler procedure would be to use the fresh water flush connection. All 7 of our Motorhomes have had one. But, if it makes you feel better, by all means continue on.

[Lantley]

Strabo wrote:

Effy wrote:
Sounds risky.

Yup allows bacteria into grey tank, bad idea. I don't ever do this, why would ya?

There is already bacteria in the grey tank. Grey water is far from sterile

[RFCN2]

When I got about half way through your post I started laughing and these words came into my mind, "what could possibly go wrong"? Plus the old Robin Williams movie where he has the "Old Faithful" moment when dumping.

So keep doing it, but please have your wife take pictures you are willing to share.