In the process of setting up my 200g reef I decided to drill a couple holes in my 56g refugium. I used the diamond dremel bits and it was much easier than I thought. The bits were around $9 each and it took one to the the holes started and a second to finish them so for less than $20 I got two holes.
If anybody has been contemplating this but is afraid, don't be. As long as you have a partner to spray water keeping it cool and go slow allowing the bit to do the cutting you'll have no problems. I do belive my tank was 1/4" glass becasue it was a bit taller than normal tanks so drillinga smaller tank would be a little toughter but I'm going to try this week on my 30g, and another hole in the back of my 200 and fix a crack in my 150g.
sweet. Do you know if tempured glass can or cannot be drilled? My Oceanic tank came with a warning that said that it had a tempured glass bottom that is good for strenght, but cannot be drilled.
Just be careful that you dont try to drill Tempured glass. could be bad
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Hardware: 37 gallon SW tank and stand by Oceanic Systems, Magnum 350 Pro Canister Filter (half carbon), CPR Bak Pak 2R skimmer, Maxijet 1200 Powerhead, RenaCal 150 W heater, Compact fluorescent lights with moonlights. 40 lbs of liverock, 3" sand bed.
Software:2 Tank-Raised Ocellaris Clowns, 1 Purple Firefish, 1 Electric Orange hermit crab, 18 Blue Legged hermit crabs, 8 or so Nassarius snails, Xenia, Blue, green, and Green Striped Mushrooms.
most bottoms are made of tempered which should not be drilled. There is a guy on RC that has drilled hundreds of tanks that claims he has drilled tempered before and will do it for a certain fee but it's at your risk of course.