looking at your other thread you recently started ...
First thing, I suggest you do some more reading on the construction threads to understand a bit more about filtration.
Your SC that you're planning will need to gravity flow to be effective ... so it needs to largely be below pond level with the top of your basin just above your water level. I see your manifold taking both BD's and your skimmer into a single SC. You have BD's at different levels since you have an upper and lower pond, SC placement [edit: and flow regulation] is going to be challenging for you, even with your ball valve manifold
From there you intend to pump through a pressurized unit ... the pressurized unit could go wherever you want it to, as it's pressurized and post pump. The thing to think through and study is the head that will be created by the pressurized unit ... the flow you need through it, etc.
However, your current plan is a little bit funky and I suggest before you go forward you try and learn some more, you'll be happier.
One way you could start thinking about your setup: if I understand, your upper pond flows into your lower pond ... you might be better off using TPR's or educators / venturis, etc. in the upper pond to sweep debris over your falls into the lower pond and have a single bottom drain and skimmer on the lower pond. Take your BD into your SC, then to your bio barrel you intend to build, then into your upper pond. A second circuit would be your skimmer, then perhaps to your pressurized filter, then to the "sweepers" in your upper pond to help you push debris down below.
Other alternative is two separate circuits for upper and lower, but again, a bigger challenge than I think you're ready for just yet. BUT, with some more research, I'm sure you can learn a ton and get it all right!!!!!!
Get reading!!