So as others have said (and I suspected), the filtration you have is:
Pump -> vortex -> matting -> plastic bio “balls” and then out of the pipes to the waterfall and back to the pond. If the matting gets overloaded with muck then it will overflow over the top of the pipes and out down the waterfall (a fail safe mechanism).
The idea is that the water in the vortex turns and like a dyson the larger solid waste particles drop to the bottom. The brushes use electro static attraction to filter the finer waste particles.
The matting then filter the last particles and should have a bacteria colony (as well as the plastic bits underneath) that then break down the liquid waste into nutrients that the plants can use.
The UV bulb discussed above acts like a steriliser (you don’t see the light) for water passing through it. It helps kill both bacteria going through it but also single cell algae that bloom if the plants can’t take the nutrients out of the water fast enough.
That pond has a lot of options that you could do - including vegetation or big filtration that passes the water through plant roots.
So initially you could get the pond up and running, then upgrade if you need depending on what you want.
The pumps are expensive and you need to look carefully at the height the pump needs to push the water up to.
If that one works - keep it and replace the broken pipe (easy to get hold of) until you’re ready to change.
I inherited a pond that was overstocked with koi, had a 2500 sized pump and a little 4500 sized canister filter - it was hell. Getting the right kit made all the difference - literally doubling the flow rate and capacity!
So I would;
* check the pump works
* replace the piping and clips
* clean the filter (don’t use detergent)
* set it running
That would get you moving at a low cost.
It will also allow you to check for issues like holes in the pond liner for the waterfall.
Measure the head height if you want to replace the pump. Factor in a drop of 1/4 of the flow rate as the pump ages (in addition to the drop caused by pumping the water up to the top of the head).
