I just completed repair to our grey tank, which failed in one of the ribs, toward the front of the tank. It appears to have happened due to flexing when the tank fills and then empties, causing the center of the rib to weaken and crack. I made the repair with a Plasti Mend kit, using the screen material and the repair goop. I also added two angle iron supports across the frame and installed blocking to fully support the tanks every foot of length.
these are the supports and blocking
this is the crack in the rib of the tank
this is the repair
this is the label on both the grey and black tanks
