Hi there! Quick question, if you don't mind. I'm in the process of putting together a 20 long with a clear acrylic top (on top of screen), held in place with foil heating and air conditioning tape. Is it ok for the acrylic aka plexiglass to be on top of the screen? Also, how much of a gap would you recommend leaving open for air circulation? We keep our home slightly cool, but comfortable. 68-ish or so. Thank you for your time!