Black and Gray tank discharge locations

[ajg617]

Just curious where the discharge pipes are plumbed into the tanks (especially black tank) and whether the tanks are flat bottom or low point at the discharge location. Dumped and flushed but site put us a bit nose high and we were still hooked up. Black and Gray empty LEDs were lit when finished. But 3 gallons into the black tank and it was reading 1/3 full.
Thanks,
John

[Cate&Rob]

Hi John,

According to the Grand Design parts lookup information, https://www.granddesignrv.com/owner-...y/parts-lookup the bottoms of the tanks in your Solitude are more sloped towards the outlet than most. See attached drawing . . . although this is not to scale. Slope is 2 1/2" in 56" according to this drawing. All tanks are very wide and shallow because of available space under the floor, so if the RV is not level, this will have an affect on draining. The level sensors (particularly in the black tank) are notorious for becoming contaminated and not providing true readings.

Rob

[ajg617]

Thank you. Just couldn't see how we could be 2/3 full in three days (2 of us) with only partial use. Started off today with 1/3 showing, not used at all, and 2/3 when we got to next site over very rough roads - which we had to level up on dump side and front but not perfect. Shallow tank explains a lot.

[pengle]

Just curious where the discharge pipes are plumbed into the tanks (especially black tank) and whether the tanks are flat bottom or low point at the discharge location. Dumped and flushed but site put us a bit nose high and we were still hooked up. Black and Gray empty LEDs were lit when finished. But 3 gallons into the black tank and it was reading 1/3 full.
Thanks,
John

Lifting the trailer front up on my 2021 310GK will actually HELP get more liquid out of the black and bath gray tanks.

[ajg617]

Thanks Pat and Karen. A little nose low but I zero calibrated it after last flush. I'm going to hold the next dump/flush for last stop if I can - they've got about 120PSI water pressure and I'll be sure I raise the nose a bit.

[Country Campers]

Thanks Pat and Karen. A little nose low but I zero calibrated it after last flush. I'm going to hold the next dump/flush for last stop if I can - they've got about 120PSI water pressure and I'll be sure I raise the nose a bit.

I would not run 120 psi water pressure through any part of the RV water system, just my opinion though.
I believe the manual has a max psi.

Brian

[Cate&Rob]

I would echo Brian’s concern about using 120 psi through the black tank flush system. The vacuum break, the flush nozzle and the soft hose plumbing are not rated for this.

The best way to keep a black tank “clean” is to always leave enough water in there to slosh about while driving. As has been discussed elsewhere on this forum, a good plan is to pre-fill the black tank with 10 gallons of water. Then minimal flush water can be used to drop toilet contents into this water where everything will dissolve and drain out easily.

Tipping the trailer to the back to help drain the black and bathroom grey tanks will prevent complete draining of the kitchen grey tank.

Rob

[ajg617]

I would not run 120 psi water pressure through any part of the RV water system, just my opinion though.
I believe the manual has a max psi.

Brian

I have a 50PSI extra regulator which I use for black tank - run 40 PSI normally through the rest. Last flush was less than 40PSI. Max in the manual is 45.

[ajg617]

I would echo Brian’s concern about using 120 psi through the black tank flush system. The vacuum break, the flush nozzle and the soft hose plumbing are not rated for this.

The best way to keep a black tank “clean” is to always leave enough water in there to slosh about while driving. As has been discussed elsewhere on this forum, a good plan is to pre-fill the black tank with 10 gallons of water. Then minimal flush water can be used to drop toilet contents into this water where everything will dissolve and drain out easily.

Tipping the trailer to the back to help drain the black and bathroom grey tanks will prevent complete draining of the kitchen grey tank.

Rob

Copy Rob. I filled with 5+ gal after last flush. 10 more nights and 1400 miles so hopefully will be plenty. Interesting the number of opinions from 3 gal up to start with. Looking at the picture of the tanks, I can wee why 3 gal might not be enough.

[pengle]

I've done the Algebra for tank filling. If you want the water to touch the wall opposite of the drain you would need to use 9 gallons of water.