# Tempered or not tempered, that is the question...



## chiroken (Sep 25, 2007)

OK, I've been picking your brains (appreciated!) on sump designs and everything for a set up 55g tank. I'm getting plumbing parts and pumps ready to order and now I'm panicking that my tank might be tempered on the back pane of glass. I've found several threads commenting 55's are often tempered all around. No stickers on any visible part so don't even know who made the tank and the store thought "maybe Hagen?" but not sure. The tank is maybe 4 years old give or take a year. Purchased in Canada.

Reading about polarized glasses (think I have a pair), LCD screens (have an iPhone and a laptop) to look for differences in the glass. Never done this before.

Question is: can you look at the glass with polarized lens with water in the tank or does it have to be air on both sides? I don't have any empty tanks laying around (all full!) to test a bottom pane to see what it actually looks like. If it has to be air I guess I can take a look during a 50% W/C but I wouldn't be able to check the bottom just to be able to actually see the difference.

Thanks.


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## lilscoots (Mar 13, 2012)

You won't need to see the difference in the panes, you just need to be able to see the pane in question that you want to drill. When you put a laptop behind it, and look through a polarized lens (sunglasses held away from your face) and tip the lens the glass will either go all black or it will have white lines/patterns in it, the trick is to turn the polarized lens slowly. You may have to do it with a water change, I'm not sure on that, I always do it with an empty tank.


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## shelbynjakesdad (Mar 13, 2013)

I think most 55s have tempered bottom and not sides. The Aqueon tanks from Petco are this way and I would guess they make up a large percentage of the 55s out there. I'm not sure how water might affect the polarization of the light... my guess would be that there wouldn't be an effect, but I'm not sure. Probably best to do as you say and run the test during a water change. Here is a link to a good demonstration on youtube:


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## chiroken (Sep 25, 2007)

OK, so I drained my office tank 50% yesterday and checked the glass with the polarized sunglasses and no black lines! (black lines = tempered) As I had already started re-filling I was running out of time. Quickly hung the laptop in and as I was close to getting it wet I "thought" I "may" have seen some black lines while also wearing polarized lens. Didn't have the time to stop and re-do so filled 'er up and was questioning the test results. So today I again drain 50% and hang a laptop on the inside and put on my handy dandy polarized sunnies and nothing, goes bright to black like non-tempered. Grab my camera polarizing lens and the same thing, bright to black. Very happy about this! As the filter at that end of the tank is splashing on the back of the laptop I decide to move it to the other end of the tank and re-check my findings and hopefully keep my laptop dry. This time I'm maybe 3 feet away from the glass rather than 2 feet and hold on a minute! What are those lines I see? Get my wife to check and we both see the same thing, black streaked lines across the glass! Not at all distances though. All the videos I watched never mentioned varying the distance from the glass so BEWARE! Conclusion is that this tank is tempered all the way around. Glass thickness is just under 1/4".

Went home to re-check my 55g grow out tank that I already did a 50% w/c this morning on (determined it was non-tempered at the time,another plus). Problem was I was at the same distance as I initially was at the office so now I don't know? Drained it 50% again and re-did the same tests at varying distance. Even had my wife check as well. Still no black lines so I am going with the grow out tank being non-tempered. Glass thickness identical to the office tank. Looks like I'll have to switch the tanks around even though the grow out tank has a few scratches....if I don't then the office tank will not get to go to a sump system (already DIY built the 18g glass sump tank) and I'd have to look into a canister filters 

So I've learned....

1) my fish have had 2 major water changes in 24hrs or less rather than weekly.

2) the distance at which you look at the tempered glass is VERY important. Had I not moved the laptop to the other end of the tank I'd have drilled it. All the youtube videos do NOT mention this, I found out almost by accident.

3) yes you can test for tempered glass through water, and through multiple panes of glass. I tested a 15g tank and it tested non-tempered. I tested a 10g tank and it tested TEMPERED. It did not test tempered this morning but again I changed the distance and black wavy lines definitely came up just now. Both of these tanks are running with water. I looked from one side with the laptop on the other side of the tank. The 10g tank has a sticker on the bottom from June 2004 that says "tempered glass". Not "all panes" or "bottom pane", just "tempered glass".

Hope this helps someone out there 1 day avoid a major mistake. I was a few splashes of water on my laptop away from drilling tempered glass.


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## Mcdaphnia (Dec 16, 2003)

I just bought four tanks at Petco's buck a gallon sale. They say that all the glass is tempered. And the label says they have made them a fraction smaller in all dimensions.


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## Deeda (Oct 12, 2012)

I checked the Marineland/Perfecto website and on their 55G tanks, all panes are tempered. The Aqueon/All Glass 55G tanks only show the bottom as tempered. Also note that this info may not apply to old tanks or brand new ones because I don't know how often they update the info on their website. I know this doesn't help a lot since you are unsure on the mfg. of your particular tank.


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