For those not familiar with a plenum here is an example.
To assemble the plenum follow these directions
1. The egg crate usually comes in 2' x 4' sheets and can be found in most hardware stores like Lowes and Home Depot. Cut the egg crate to size (A pair of heavy utility scissors works well.)
2. Place the Egg Crate panel on a flat surface..
3. Attach the PVC pipe rails to the egg crate using nylon tie wraps (no metal).
4. Attach the PVC pipe ends to the egg crate.
5. Space the PVC pipe supports evenly on the egg crate and attach.
6. Turn the assembly over.
7. Cut a hole in the Egg Crate large enough for the 1" riser tube to fit into. This hole can be anywhere you want it.
8. Cover the assembly with the larger piece of nylon screening and tie-wrap in place. It should hang over the sides.
9. Cut a V-shaped grove in one end of the riser tube with a small saw. This will allow the riser to sit on the bottom of the tank while water moves freely.
10. Cut the screening where the riser tube goes and insert the riser tube with the grove in first.
11. Place the plenum assembly in the tank and center it.
Cover the plenum with approximately 1 to 2 inchs of CaribSea "Seaflor special Grade Reef Sand.
12. Lay the smaller piece of screening in the tank centered. This helps keep burrowing critters from disturbing the bottom layer of sand.
Cover the screen with the rest of the CaribSea "Seaflor special Grade Reef Sand.
13. Install a Power head on the riser tube and run it until Amonia and Nitrite readings are undetectable, then remove the power head and riser tube.
Images:
http://i163.photobucket.com/albums/t.../PlenumTop.gif
http://i163.photobucket.com/albums/t...PlenumSide.gif