Pumps needed for skimmer? pump routing? I need a start!

[theedudenator]

I have all this used stuff.. I am trying to figure it out.

Large skimmer sits in the bottom tank
Large skimmer has 250g/h pump near the bottom
The pump has an air inlet for a bubbler
This sucks water from sump tank into the skimmer
I understand how and why on this set up.

I have another 740g/h pump that sits in the sump tank and pushes water into the TOP of the skimmer. This actually flows directly to the bottom of the skimmer. I do NOT understand what this pump does.

I have another 500g/h pump that is loose - supposed to sit in the sump.
I guess this pushes water back to the top 120gal tank?

Where do I route the UV tube?
inline with the return line back to the top tank?
Inline with the syphon line down to the sump tank?
Separate pump that runs in and out of the sump tank?

This is the skimmer that I have

http://www.superskimmer.com/etss_evolution_500.htm

 

[theedudenator]

I have some photos of my plans... Any suggestions?

I am attaching some sketches of what I plan on doing.
I will be buying some lexan to make baffles

 

[theatrus]

You may have a recirculating skimmer (maybe?). These type have a much smaller feed pump to supply them with water (enters 2/3rd the way up, exits on very bottom, and the bigger air injector pump which recirculates the water in the skimmer and produces the bubbles/foam.

 

[austinsdad]

Check your UV choice for recommended flow rate. That'll help you decide where to plumb it, but I'm thinkning the main return line might be too fast a flow, thereby getting nothing from the UV.