drilling an older glass aquarium

[Itz Irish]

my aunt and uncle recently gave me a 40 long aquarium, and i would like to drill it and make a 15 gallon sump. my question is how do i know if the glass is tempered or not?? i dont know the year of the tank or anything. the glass is just under a half inch thick. any input??

[Mizer67]

I have heard that if you see an interference pattern when you look at glass through a pair of polarized glasses, it is tempered. The only problem is, if you don't see the pattern, it doesn't prove that it isn't tempered. Be careful if you try to drill, protect your eyes and hands just in case it does let go. Good luck.

[kgross]

Can you find a sticker from the maker? If so try contacting them to see if it is tempered. If not, you can try the polorized trick and hope.

Kim

[wolf pup]

I tried the polarized glasses trick on a 55 gal. Looked clear as day but 30 seconds into drilling "BOOM" - glasses and gloves saved the day. Just be prepared for a suprise or at least cross your fingers if you can't confirm from the manufacturer that the glass is not tempered. (BTW - my .02 would be that it is tempered unless they remember buying it within the last 5-10 years.) Stay safe in whatever you choose to do.

[kgross]

If you are going to try the polarized glasses trick. Make sure you check some known tempered glass so that you know what you are looking for. The window on your car/truck is a god known tempered piece of glass that you can test with. Once you know for sure what you are looking for you can that techniqe to test the tank glass.

Kim