<a href=showthread.php?s=&postid=7436016#post7436016 target=_blank>Originally posted</a> by lactose
I guess I should have been more clear.
I meant that the saw or drill could be used to 'fix' the size of the rock not the size of the opening.
When it comes to the main display tank that holds lots of water up high above precious things - like my floors and children - I have to admit that I am very hesitant to attempt to harm its structural integrity in any way.