Individual gray tank capacities?

[RVHauler]

Hi all,

I'm trying to determine the two individual gray tank capacities in my rig, asked Keystone but they only have the combined total.
I have separate galley and bathroom tanks.

The total they gave me is: 87 Gallons.
TIA

~Lou
2016 3000RE

[Daryles]

Having had the forward bottom coroplast off to work on the black tank valves I can tell you the black tank and the grey 1 (bathroom) tank are identical. The brochure for the 2019 model says the black tank is 49 gallons. Assuming the grey 1 is the same, brochure says total grey capacity is 88 gallons. This means the grey 2 (galley) tank is 39 gallons.
One way to be sure is put a meter on a garden hose and fill the tanks.
To get more capacity, install a Valterra twist on gate valve at the end. This will give you about 6 gallons altogether in the 3" sewer pipe.
You can also use it to empty the galley tank into the grey 1 or black tank or both by keeping the gate valve closed and opening the galley valve for a few secondsand open either of the other two valves to let the galley drain into them.
I use this method to back flush the black tank when dumping. ONLY when you have more volume in the grey tanks than black tank. In other words, dump the black tank first.

[RVHauler]

Awesome, thank you. Makes total sense about the sizes.
Would love to see any photos with the coroplast off?
I've got the screw-on valve, have contemplated connecting the two grey tanks if I ever had the need for more capacity in either for boondocking.
I think I have inadvertently backflushed the black tank in that manner when I forgot to close it and opened the grey tanks to flush the sewer hose LOL.

[rohrmann]

Originally Posted by RVHauler

Awesome, thank you. Makes total sense about the sizes.
Would love to see any photos with the coroplast off?
I've got the screw-on valve, have contemplated connecting the two grey tanks if I ever had the need for more capacity in either for boondocking.
I think I have inadvertently backflushed the black tank in that manner when I forgot to close it and opened the grey tanks to flush the sewer hose LOL.

This is a photo of our black and grey tanks when I made a repair to a crack in the bottom of the grey tank and added supports to both. The problem with connecting the grey and galley tanks is that the grey is usually located in the drop frame area and the galley is located higher toward the rear of the rig, so the galley tank will not fill until the grey is full.

[Daryles]

I have a 2019 3130re so my tanks will be different from yours. I believe they went to one piece "rotoplast" tanks in 2018 or 19.
They are mounted differently too but the pipes and valves are the same.
While I had the bottom off I added 1" insulation (silver stuff) around the frame perimeter and bottom to help prevent freezing while winter camping.

SmartSHIELD -20mm 48"X25ft Reflective Insulation Roll, Foam Core Radiant Barrier, Thermal Foil Insulation Panel - 0.8 Inch Thickness, R-23 https://a.co/d/doAuEEx