Delaware Reef Club

When a Fellow Reefer needed a hole drilled it seemed like the perfect opportunity to explain how to drill a glass tank. The pictures below are from Cdangel0 75-gallon build along with his 20 long fuge tank.
One of the first requirements to even starting this project is to determine if you are capable of doing it. It will require tools (diamond bit, drill) and a lot of patience. This is one job where it is not a race to the finish.

 Determine if the tank can be drilled.

Not every tank can be drilled. There are standard plate glass and tempered glass tanks. Some manufactures label their tanks but a lot do not. If you are unsure contact the manufacturer or search on the internet. DO NOT DRILL UNTIL YOU ARE SURE. The difference becomes apparent if you have ever broken both types of glass. Tempered glass breaks in a unique way. If any part of the glass fails, the entire panel shatters at once. This distinguishes it from normal glass, which might experience a small crack or localized breakage from an isolated impact. Tempered glass might also fail long after the event that caused the failure. Stresses continue to play until the defect erupts, triggering breakage of the entire panel.   YouTube video,Tempered Glass  Although the video uses a Dremel the principal is the same; If you drill a tempered tank it will shatter.
If the tank is older and you can't find any info on whether it is tempered or not I have 2 suggestions to test for the glass being tempered. Put the tank outside on a bright day and with a pair of polarized sunglasses look through the tank if you see what appear to be little circles or squares the tank is tempered. Another way is to use a glass cutter. In the spot you want to drill apply some cutting oil to the inside of the tank. Using a glass cutter, roll it across the glass. If the glass cutter scores the tank it is most likely not tempered if it leaves no mark then it is hardened and tempered.

Its always surprising to me to see the responses to questions like this. When ever any other water parameter question is asked the replies are usually in-line with natural sea water values but when temp questions are asked the replies are to keep temps at values that are lower then found in nature and and to keep any temp fluctuations to a minimum or even static.

Why would we want temp to be any different then what the animals would find in nature and have evolved to over thousands of years?

Myth - The ideal temp for reef tanks is about 77-80

The worldwide average for coral reefs is a wintertime low of 77 to a summertime high of 86. The overall yearly average is 82. The average temp in the coral triangle where reef diversity is highest (and the majority of the livestock in the hobby is collected) is around 82-83 depending on the source. The thermal optimum, which is the temperature where a species grows best, has been tested for a handful of corals and for almost all species falls between 82-84.