Originally Posted by kribbz
you could take it to a glass shop and have them drill a hole for you in the glass so you don't have to mess with any sort of syphon.
This would be your best option. You would probably have to have it drilled in the back glass though as most 55gal and up tanks have tempered glass bottoms and cannot be drilled. You could either have it drilled at the level you wanted the water to stay or you could have it drilled low and install an internal overflow box to regulate the level. This would essentially make it a "reef ready" tank.
If you do go with an external overflow, I like the U tube types best. This one looks good to me as suggested above.
It says they are out of stock though. You might check with Darin at Captive Reefs or I can see if I can get you one through my wholesaler if that's what you decide to go with.
The external siphon type offers easy installation and quick setup...takes about 5 minutes to get it going. It has a higher potential for a mess though if the siphon ever fails. The internal will take up a little more room inside the tank, will take longer to set up as you'll have to have the tank drilled and silicone in an internal overflow, but it will cut the chances of the tank running over to almost 0. I would say the prices will be pretty close on either method.