I used the stainless steel meshes that Buckeyemolded (Robert) generously gave me during one of my purchases from him. I had about (3) 3x3" meshes with moss on them in a 29 gallon foreground. Water changes every 2-3 weeks. No deaths between my cherries and crystals with mesh being in there for almost a year.
From the
pictures on Robert's site, he also keeps a good portion of his tank lined with the meshes with cherry shrimp. So at least I pretty certain that the mesh he uses (and ocassionally sells) doesn't cause any problems.
-John N.