Is it tempered???

[CAM6467]

I just picked up an older 30 gallon Oceanic-Systems aquarium off of Craigslist the other day. I'm wanting to try drilling the tank for hidden plumbing, but I have no clue if it's got tempered glass or not. My gut instinct says to stick with standard filter pipes hanging over the back edge, but I really want to have the bottom drilled for the hidden plumbing. Anybody have any helpful advice or suggestions?

[kid creole]

I can't vouch for this page, but they say it is not:

http://alysta.com/books/fishtank.htm

All tanks can be different. If I got the tank off of Craigslist, I think I would go ahead and drill. If it's tempered, oh well. JMHO.

[Wasserpest]

That table isn't very useful.

Your best bet would be to look for some manufacturer specific information, perhaps call Oceanic, although if you don't know when it was produced it might be difficult.

[Hoppy]

If I remember right, you can check for tempering using polarized light. I wonder if polaroid sunglasses would work for that? I'll bet Google would come up with the answer.

[Postal Penguin]

From Wikipedia: "The strain pattern resulting from tempering can be observed with polarized light or by using a pair of polarized sun glasses."

I dont know what the strain pattern looks like. But perhaps look at glass you know not to be tempered and compare.

[speedie408]

If the pattern looks anything like what I see when I wear my polorized glasses, it will look like a checker/chess board when you look at it. Thats the best way to put it.

[dbosman@msu.edu]

When in doubt - unless you can afford to lose it - don't drill.

Another thing to check is along the bottom rim. Some manufacturers put a sticker saying tempered under the bottom, on top of the plastic rim.

[CAM6467]

hmm.... I have seen those wavey looking lines in the tent of my truck's windows when I wear my polarized shades. I always thought that it was just the tent on the windows, though. I'll give this a shot. Thanks a million for the little trick!

[lovingHDTV]

Originally Posted by speedie408

If the pattern looks anything like what I see when I wear my polorized glasses, it will look like a checker/chess board when you look at it. Thats the best way to put it.

Cool, this must be the pattern I see on car windows when I wear my polarized sunglasses. I always thought I was imagining things. I guess I'm not crazy!

[691175002]

Technically you need two polarizing filters.

Tempering is when you intentionally stress glass, stressed glass can turn the polarization of light.

By putting a polarizing filter in front and behind the object you will see dark spots/variations in color where there is stress. You are essentially building a polariscope.
http://www.ecu.edu/glassblowing/glassstress.html

You might be able to notice a difference with only a single filter, but I have never tried it.

[sick lid]

Originally Posted by Wasserpest

That table isn't very useful.

Your best bet would be to look for some manufacturer specific information, perhaps call Oceanic, although if you don't know when it was produced it might be difficult.

No, it's not very useful. It lists a 180 as not tempered. Mine is.