20L devided mantis tank

[speedsport]

I'm starting 20L mantis tank. I want to do a false wall and devide the tank so I can have 2 mantis in the tank. My question is how do you guys think I can do this? Like the depth of the back chamber and stuff. I was thinking of going like 3-4in for the rear chamber. For the devider it will be able to flow water through it but not let the mantis get through. I will have a skimmer in the back and a fuge. I will run 2 65w CFs and I will keep zoos and stuff like that. Any thoughts or opinions would be great.

Thanks

 

[gussy]

I've used egg crate with fiber glass screen for temporary purpose...couple of months. For a permanent one, I am planning to have acrylic with strainer type slits.