So I've been going around asking a lot of people about filtration on a 4000g+ pond that I am hoping my dad won't shoot down the moment I open my mouth 
So I had the BRILLIANT idea.
Basically, I was going to have a raised area around 400-600 gallons. I would then have another body of water about 2-3ft underneath and in front of this body of water. I would have a pump running from the end of the pond to the top of the raised area which would then cause it to fill because the main area of the pond would be 4000 gallons. I would create the front of the raised area lower than the rest of the edge by a couple of inches so that when it starts to fill up then it would spill out of this lower area over rocks, and stuff creating a waterfall! So now, what I thought of was filtering this raised area with a canister filter (homemade) which would then flow into the main pond and then would be brought back by the pump and viola! Filtration! My question now is, what gph would I need the pump to be...And how should I approach making the canister filter? I've attached a picture that I just drew up on Paint
It might, or might not help you visualize it.

So I had the BRILLIANT idea.
Basically, I was going to have a raised area around 400-600 gallons. I would then have another body of water about 2-3ft underneath and in front of this body of water. I would have a pump running from the end of the pond to the top of the raised area which would then cause it to fill because the main area of the pond would be 4000 gallons. I would create the front of the raised area lower than the rest of the edge by a couple of inches so that when it starts to fill up then it would spill out of this lower area over rocks, and stuff creating a waterfall! So now, what I thought of was filtering this raised area with a canister filter (homemade) which would then flow into the main pond and then would be brought back by the pump and viola! Filtration! My question now is, what gph would I need the pump to be...And how should I approach making the canister filter? I've attached a picture that I just drew up on Paint
It might, or might not help you visualize it.
