By Chris Carter

Materials required

• Nylon or Fiberglass window screen
• Silicon adhesive
• Magnetized rubber strips. (Those thin refrigerator magnets that your dentists and insurance agents like to give you work great)
• Several small brads or upholstery tacks
• Towel to use to clean hands and wipe off excess silicon

The idea here is to close the back of the hood so that fish can't jump out of the tank while still allowing the ability to slide to hood forward and backward for tank maintenance. Using window screen will also still allow good air flow and thus help to dissipate heat build up.

1. Cut the window screen to size. Width: the window screen should be cut such that is slightly narrower than the overall width of the hood. Height: the screen should cut such it is a slightly longer than the total height of the hood. You want the screen to hang down about 3/4" to 1" below the top edge of the tank.
2. Affix the screen to the back of the hood. Lay a medium size bead (3/16" - 1/4") of the silicon adhesive around the back of the hood. Center it along the edge of the boards your hood is made from.
3. Secure the screen to the hood. Starting at one of the top corners place the screen on top of the adhesive. Make sure that the adhesive bead is completely inside the edges of the screen. Use one of the small brads to hold the screen in place while the adhesive sets. This brad can be removed later so do not drive it all the way in. Go to the other top corner and secure the screen with a brad there also, pulling the screen tight across the top of the hood as you do so....BE SURE THAT YOU square things up. Run your finger across the top to firmly embed the screen in the silicon. Secure the screen with brads at the bottom of each side of the hood AT A POINT that is higher than the top of the tank. When this is done the screen should be fairly taunt across the back of the hood (except of course for the unsecured bottom)
4. Place the hood on the tank. I recommend opening it and setting back a little becuase you still have to make cutouts for you plumbing and stuff like that. Make the necessary cutouts and slits for your plumbing, power cords and the like.
5. Move the hood up to its normal place and check the fit of you cuts. They don't have to be perfect but the screen should hang reasonably straight.
6. Secure the bottom of the screen. Here is where those magnets come into play. We are going to silicon them to the screen and the top edge of the back of the tank. This part is a little messy. Cut the magnets into strips that are equal sizes. I suggest no smaller than 5/16"x1-1/4". Stick them together in pairs so that you can easily align them properly. Holding one of the stuck together magnet pairs by the edges put a bead of silicon on each visible side. You can now place the magnets between the screen and the top edge of the back of the tank. Press firmly on the screen to to embed it in the silicon and to get a good seal against the back of the tank. What you are going to end up with here is magnet sets where one magnet is siliconed to the screen and its sister magnet is siliconed to the tank.
7. ALIGNING the magnets: I suggest that you put a set of magnets on each side of any cutouts you made. I also suggest that you fill in any long runs by placing a magnet set at least every 12"
8. Don't move the hood for at least 24 hours. You need to give the silicon time to cure. After 48 hours you can remove the brads.
9. Once the silicon has cured you should be able to slide the hood forward and back and the magnets should break apart easily. When you slide the hood back in place the magnets shoudl attract each other and automatically seal the back of the hood.