Setting up my pump and filter(s)

[Lugnut]

Hello all,
I will try to get some pics up soon to show my project, but for now I need a little help on my pump and filter. I have an upper pond(about 1000 gallons) that flows into the lower pond. I have a waterfall that flows into the lower pond. I want the waterfall and upper pond to flow with a lot of volume. My question i guess is, if I put a bio filter between lower pond and waterfall will my flow be too fast for proper filtration? There is no room for a gravity fed bio filter between lower pond and upper. Where do I filter? Do I need to have water to the upper pond, waterfall, and a smaller amount to a biofilter that runs back to the lower pond? 2 pumps or one? Sorry for all the questions, but I have no more brainpower to solve this. Currently I have been using a 3600 gph harbor freight sump pump temporarily until I decide what to replace with. That particular pump barely has enough volume for me. Unsure if it is a lack of quality or I simply need more gph? Thanks for all who made through the whole message!:

 

[DrDave]

I use a Beckett W1150 for my bio filter that is inside my waterfall. I also use the same HF pump as you to send the lower pond water up to the upper pond. They are connected by a stream that the waterfall also feeds with the filtered water. Does this help?