Flushing black tank

[BuckeyeChuck]

When I dump my black tank I flush the tank while it is dumping using the black tank flush feature on my camper. My question is is it better to leave the dump valve open while Flushing or should I close it let the tank fill and then dump it again?

[David N Dianna]

If you are not holding up a line for the dump station, Fill and dump repeat as need for clean discharge. (clear fitting)
Remember gravity and head pressure are your friends when dumping the black water tank

[5picker]

Just don't walk away or get distracted while flushing if closing the valve!

We've seen reports of 'Ol Faithful' spewing out the roof vent.

[ependydad]

Originally Posted by BuckeyeChuck

My question is is it better to leave the dump valve open while Flushing or should I close it let the tank fill and then dump it again?

If you close the valve, you run the very real risk of forgetting and 1 of 3 bad things can happen:
1) the tank ruptures at the seam where the top and bottom of the tank come together (had this happen to a friend)
2) the water fills up the vent tube and starts running down the roof and side of the camper (helped a fellow camper when this happened to them)
3) someone happens to press the pedal and you get a poo "explosion" that floods the bathroom and/or person who stepped on it (we lucked out, it stopped 1/2" from the top of the toilet)

If you leave the valve open, the tank isn't as well flushed. When we flush, we leave the water run for a bit with the valve open. We then close it and let it fill (5-minutes worth of water) before opening it, we ALWAYS see more TP come through when doing that. Just flushing with the valve open does NOT clean it out fully.

[Kaadk]

Officially, they say you should ever ever run it with the valve open.

That said, I do find you can get a better flush if you let it refill by closing the valve and then draining it again. However, if you do this, you need to use a lot of caution. If I close it, I set a timer on my watch for 2 minutes so I remember to go back and drain it again. I've been very skittish about doing so after my own experience with a flush failure:

http://www.forestriverforums.com/for...ush-67565.html

[timfromma]

While not 100% accurate, I close the black valve and monitor the LED level indicator. I reopen once it shows full. I find that 2 water fills and dumps leaves the tank pretty clean.

[BuckeyeChuck]

Thank you for the replies. I can always count on this group for good answers to my questions. In the future I think dump the tank close the valve rinse the tank for 4 minutes dump it again close the valve rinse it again for 4 minutes then dump for the last time.

[timfromma]

When in doubt, open the toilet valve and look. If you see water, you're full.

[5picker]

Tim, you trust those notoriously inaccurate tank level indicators way more than I would.

I put one of these on the flush hose and use it to put 20-25 gallons in the tank.
No need to run inside and see if the tank is possibly getting close to full.

[timfromma]

Originally Posted by 5picker

Tim, you trust those notoriously inaccurate tank level indicators way more than I would.

I put one of these on the flush hose and use it to put 20-25 gallons in the tank.
No need to run inside and see if the tank is possibly getting close to full.

I use them as a rough guide. I couple the level indicator with looking down the bowl.

[fella10]

Originally Posted by BuckeyeChuck

....My question is is it better to leave the dump valve open while Flushing or should I close it let the tank fill and then dump it again?

Depends, ... depends on where your tank flush unit is located, ... mine(and probably yours and most FR installs) is mounted above the drain outlet, SO if your valve is open and draining while spraying, its easy to understand the flow out is being hindered by the spray into that flow going out, not with that flow, ... if the flush unit is mounted on the opposite side(but its probably not) then spraying with the valve open would be helpful, because the spray would help push the solids and paper towards the drain hole, ... with mine mounted above the drain outlet, I have found the best results I can get are by: ... closing the valve, spraying (yes, you do have to be attentive when doing this) the amount of water you want, and then stop spraying and open valve, let drain, ... repeat as necessary, ... this isn't perfect, but when the flush unit is mounted above the drain hole, this gets better results than spraying with the drain open, ...