I just installed a small pond 155 gal, im getting weir waterfall filter how much of a pump do i need. thanks

Question:

Answers:
The rule of thumb for aquariums is to pump the contents 4 times an hour, hence you need about 600 gph pump or higher if you are pumping it up more than a couple feet.
At 4 feet height, your pump will be at reduced flow about 20%