[Canadian Man]

Tony, I dont think your 90"s are the problem,
I have 1 90 and quite a length of pipe before the pump. But then again i have a 1.5" bulk head in the tank i got from you.
could be it.
yes
now that i think of it the pump may be stressing to try to pull that much through the 1" bulk head.

cut back the output of the pump for a few hours/minutes and see if the slower flow helps with that problem.