2: The Divider
You need to determine how much of the sump will be needed to house your Protien Skimmer and it's associated pump (if applicable) and your return pump.. Then divide the sump by adding a section of 3/16' Plexiglas or 1/8' Acrylic (fit it snug enough (front to back) to hold itself in place for gluing)) and keep it off the bottom of the tank by 1' to 1 1/2' (for water flow).. Run a bead of silicon sealant along both sides of the divider where it meets the front and back glass..refer to the diagram above..

If the Divider fits snuggly enough you can continue to the next step.. If the Divider moves easily, allow the silicon a few hours to cure before proceeding..

3: Support Plate Strips
Cut 3 separate 1/2' strips of plexiglas or acrylic. These are only for supporting the filter media support plate so, they don't have to be perfect or pretty :-).. Refer to the small squares under the media support plate in the diagram.. The top of these strips should all be fairly level (not critical) and should be no higher than 2' off the bottom of the tank.. Place a bead of silicon on one side of each of the 3 strips and place one on the right end of the tank, then attach one to the back of the tank from the right end to the Divider.. The last one goes on the divider from the back strip to the front of the tank..The media support plate will be placed on top of the 3 strips after the silicon has had time to cure..

Looking down into the sump you'll see a partitioning divider that is 1' to 1 1/2' off the bottom and the support strips 2' off the bottom along the right side, back and the divider..

4: Media Support Plate
Measure the inside space between the right side glass and the Divider for the width of the Media Support Plate and measure the inside space from the back to front minus 3/4' for the depth.. Place a bead of silicon along the top edge of the 3 support strips (installed in section 3) and place the Media Support Plate on top of them (leaving the 3/4' gap at the front glass (for water flow))..

5: Trickle Plate
Cut a piece of plaxiglas or acrylic to loosly lay on top of the filter media (roughly 1/2' to 3/4' narrower than the width of the Media Support Plate).. You'll need to drill several dozen 1/4' to 3/8' holes in this piece to make it a Trickle Plate..

Don't be in a hurry while drilling these holes or you'll break the plate.. I use a filter pad designed for use in pond filters.. 3/4' to 1' thick and cut to size..

6: The Sump Cover
You'll want to cover 50% to 75% of the top of your sump to slow down on evaporation and to prevent water from splashing out of the sump onto your floor and electrical outlets.. Take the necessary measurments from the inside lip of the tank and cut your plexiglas or acrylic to fit.. Drill a hole in this cover (over the center of the Trickle Plate) large enough to accept your water inlet from the overflow boxes..

7: Additional Notes
I have this same sump set-up here using a 10 gal sump for a 55 gal tank and it's perfect.. No problems with heat differential unless you had a really slow return rate.. I use an RIO 2100 pump/powerhead for the return pump..

Use a set of overflow boxes (available through any good LFS (Local Fish Store)).. Use 1/2' CPVC pipe and elbows and 5/8' inside diameter plastic hose/tubing for the return line.. Drill a 1/8' hole in the return line at the main tanks water surface to allow the syphon to be broken if the power should fail..

I have my protien skimmer in the left compartment where the return pump is also placed.. I use a separate powerhead for the return and skimmer.. The skimmer doesn't get all the water on the first pass but it does equalize as the water from the tank is mixed with the cleaner skimmed water from the sump and more tank water is mixed in the sump.. The whole set-up equalizes in 15-20 minutes, after the water starts flowing.. The skimmer is simply a part of the system wheather it's located in the sump or outside the tank.