I am having trouble selecting a pump for my drywell going under the gunite pool. Essentially I have a 2" perforated pipe buried in gravel going beneath the deep end of my pool shell. I want a positive displacement pump to mount at the equipment pad to pump water out from under the shell in the event I have to drain my pool. I thought I had the right thing, it's a diaphragm pump that can prime up to 10' vertically (pool 5' 6" deep) but upon connection, suction does not seem to be enough to get the water up and out. I pressure tested the plumbing down to the point of where the pipe will go under the shell and it's fine, so I am guessing I bought the wrong pump. Anyone with experience here can point me in the right direction? I have a shurflo 120v diaphragm pump, is there a better one that has more pull?