dmpfishlover
Fishaholic
If your tank has a lid/cover, and you design and make the divider yourself, you could easily make sure it extends above the surface of the water and meets the bottom of the tank cover.. That is if you are set on dividing a tank for shrimp and a Betta... The other option, which might be more expensive initially, but will probably be less of a hassle in the long run, would be to just use separate tanks for them.... If your like the rest of us with MTS (Multiple Tank Syndrome), you probably don't need much persuasion to get another tank.