Where on the tank should i drill?

[Chrispar]

So after reading a bit ive decided im gonna drill my tank to drain into the sump, i plan on making my own internal overflow, but my question is should i drill low on the back of the tank or go ahead and do a hole on the bottom of the tank and do a durso pipe?

i do not wanna go with a HOB overflow because im scared of losing syphon and having a flood

[Zarathustra2]

Personally, I really like the "calfo style overflow" and would set that up if I had bare glass and a diamond bit to work with. You drill multiple holes near the top of your tank and have a loooong skimmer box to collect the water. Since the water only drops a inch or two no need for the durso pipe. Downside is you cannot put heavy water pressure on the drain so you will have to make sure you drill enough holes to more than make up your flow. Also 1.25 or 1.5" drains are a very good idea.

[Gonzobob]

As Zarathustra implied, the type of overflow you want will largely define how you want to position your bulkheads. There are a lot of online resources defining the advantages and disadvantages of each type of overflow.

Take time, do research and by all means drill once:)

[prof]

Most tanks have a tempered bottom pane. This cannot be drilled. It is always best to check with the aquarium manufacturer to see what is tempered and what is not.