Upgrading 29 from standard to overflow with sump - need advice
 

I'm ready to get rid of my 30x12x18 acrylic 29G and get a glass with overflow and sump.

My LFS can drill the back of any 29 glass (because the bottom isn't tempered), but they said it's loud because of gurgling if drilling in the back.

They can custom order me a 29 drilled through the bottom but it's considerably more money (almost 2x as much).

Is it true that bottom drilling is better than drilling in the back?
Is there a way to make the "gurgling" quieter if drilled in the back?

Any advice or "I wish I knew now what I know now" when setting up an overflow?

Thanks.

Jota:
Why are you thinking of switching to a glass tank to drill for an overflow for a sump. Your existing acrylic tank is far easier to modify and won't nearly as much risk of cracking. The LFS is right, a bare bulkhead on the back of the tank will be extremely loud and annoying. So will a poorly designed overflow. I made one in my tank to go around a bulkhead in the back wall that was only 2x3 inches. Needless to say, this is impossible to work with and will soon be changed to a larger box on the outside of the tank. There are many ways to make and overflow, and at least 4 named methods for quieting the gurgle caused by the drain: durso, stockman, and the newest, the "hofer gurgle buster." search for any of these on RC or on google and you will come up with some good hits.

by 4 i meant 3 methods...

Thanks for the reply thrill. Well my setup is about 6 years old so my acrylic tanks has a hefty amount of minor scratches. Also, it takes a considerable amount of time to clean it, whereas glass is much easier and faster to scrape the walls.

I will definitely research all your methods listed.

This is the first time I'm going in this direction for my fish tank, so even though I've got decent experience it's not in overflows or sumps.