Hole saw anyone?
 

Does anyone have a hole saw?
Would you mind drilling a hole in my 30?
I don't need or want to buy one right now...

I think only the professionals use diamond hole saws which are not meant for portable hand-held use. For DIY, we all use Dremels with diamond bits. Not nearly as perfect, but the bulkhead will cover up any ugliness.

I read those posts...
What were the Bit numbers again?

Should run the dremel on a lower speed?

Also, is there a way to tell if a piece of glass is tempered?
I once took a piece to a glass cutter and they looked at it from the side (width wise) and was able to tell if it was tempered...

Sorry, I don't know Dremel's bit numbers. Maybe someone who knows from memory can chime in. I used no-name brand bits which are pretty much disposable. Took me 2 bits to drill a 2 inch hole in a 77 gal. No great loss at 2 bucks each. You'll need a 'round' boring bit to drill a hole, and then a cylindrical to do the cut-out. I ran the Dremel at full speed and lots of water. You may need a helper to keep the bit wet with a spray bottle. Both should wear eye and ear protection.

Pros use cross polarizers to see little square patterns on the glass to find out if it's tempered. I remember reading something similar about looking at the glass' edge too, but I can't remember! There's a very high chance that a 30 gal will not be tempered. Unless it's custom order, not too many tank makers would hike up the price tag for no apparent reason. IF there is a piece that's tempered, it would be the bottom piece before anything else.

I believe the Dremel numbers are 7134 or 7144 and 7104. But, if theres a Princess Auto in your area, I picked up 30 diamond coated bits for $5. At $15 a piece for Dremel bits, you're getting 15 times the bits at 1/7th of the cost (after tax). They worked great for me. Did 2-1 inch holes and theyre as good as new. HTH.
Sean