I got a question regarding why would you cut plastic and glue it in the AC500. Basically, plastic inserts or baffles reduce the current in the AC so any live sand or rock isn't disturbed and in turn doesn't kill your impeller/motor, cloud your tank, etc.
I'm sure if you searched for AC500 or AC300 fuge on canreef you'd find lots of info.
Here are some links that also helped me out on nano-reef.com.
http://www.nano-reef.com/forums/sho...;threadid=52245
http://www.nano-reef.com/forums/sho...;threadid=16635
http://www.nano-reef.com/forums/show...ighlight=ac500