Cutting Glass

[eric-c]

How can I tell if I can drill a hole in my tank? It's a 45gal corner pentagon and I'd like to put an overflow in the back corner of it.

 

[JayM]

most tank makers only temper the bottom glass...but YMMV.

 

[maurod]

Who made the tank, contact the manufacturer to be sure.
M

 

[eric-c]

What does YMMV stand for?

 

[JayM]

your mileage may vary......

 

[NateHanson]

(moved to DIY forum).

There's a way to use two polarized lenses (like sunglass lenses) to tell whether a piece of glass is tempered. I don't know what the particulars are though.

Can anyone say how you do it? I expect a google search would find the answer too.

 

[stevenp]

With polarized lenses, you can normally see a pattern from when the heat was applied. I think it's because they lay the glass on a grid when they blast it with heat. It's usually pretty obvious, at least on automobiles. I've never tried to inspect aquarium glass however.

 

[Scott]

(moved to DIY forum).

There's a way to use two polarized lenses (like sunglass lenses) to tell whether a piece of glass is tempered. I don't know what the particulars are though.

Can anyone say how you do it? I expect a google search would find the answer too.

I was curious, so I went looking:

Take two photographic polarizing filters.
Sandwich them together. Rotate one of the filters. Light transmitted
through the filters will fade from lighter to completely blacked out as the
planes of the polarized material crosses through each other's axis. Now, try
the same thing with the piece of glass sandwiched between the two filters,
and rotate one of the filters. If the glass in untempered, the light
transmitted through the filters will act the same way, fading from lighter to
blacked out. If the glass IS tempered, an interesting phenomena will occur:
as the filters are rotated, a black cross will form through the filters.
It's an unmistakable sign: if the cross is there, the glass is tempered.

what if an image of Mary appears?

 

[NateHanson]

Thanks for looking that up bonz. Sounds easy enough. I sit on my sunglasses often enough that I've always got a couple loose polarized lenses lying around.

 

[eric-c]

I did check with the manufacturer and it in fact is tempered at the bottom. I guess the safest thing is to get a overflow box. It’s probably better that way, it’s only a 44gal tank, I need all the room I can get!

Thanks for every ones help though.

 

[NateHanson]

Your tank might be a good candidate for an external overflow box, because of the limited interior space. You would drill a couple holes near the top of one pane, put a comb in front of them inside the tank, and then silicone a glass box to the outside of the tank that has your durso, or equivalent drain inside it. The bottom of that box would have a hole for the pluming to go down to your sump. Pretty easy to do with glass cut by your local glass shop, and worlds better than a siphon overflow for reliability and looks.

 

[eric-c]

Well thank you every one, I have enough to go on now. Whether I’ll go with the external overflow or get the siphon overflow is still to see. I will consider both though.