Thank you for the above,
i have a bunch of neocaridina tanks, but opaes are so diffrent, :D
From reading threw this site, and a few other bits, i might try somthing a little diffrent, and just go with a rock wall on the rear of the jar, and the cave built into the base of the wall. i liked that idea.
Now the hard part, to find a 8-10l strait walled jar
when i finaly get started, i am sure i will be posting a bunch of questions and show off photos( best part of any forum:D
Thank you again for the help.