Originally Posted by bayview
support the hose somehow. I suspect that vibration or pump action causes the hose to move and lever that tank fitting.
Agree. Looks like fatigue of a glassed in metal nipple in the tank. Often times there is a flat ring welded circumferentially on to the nipple that gets glassed in.
Watch it while pumping out. My hose bucks pretty good when pumping out with a macerator in what we call slug flow in the engineering world. If you use a positive displacement diaphragm pump, it would also have discontinuous flow which could lead to fatigue failure.
One could strengthen it with gussets to the tank top. Be a pretty tedious glass or epoxy job though.