Mystery Glass?

[NOI7734]

Hello all,
Please forgive me if I forgo any formalities here this is my first post, but I've been skimming the forums here for quite some time as needed

So a little background of the issue at hand; I purchased my 125g glass tank used, water tested, etc etc. Got it cycled and transferred all my fish from my 55g, not long after that my 125g starts leaking out the side, ahhh! I now have all my livestock back in the 55g, the 125g is drained and I'm in the process of removing all the old silicone with the intention of separating all the glass and rebuilding the tank entirely with RTV-108. I figure while I've got it all torn apart, I may as well set it up right with a sump since I have the space in my stand, this brings me to:

The Problem:
The bottom pane of glass makes no mention of the word "Tempered", however, it proudly displays the name "PPG Herculite K", and all the googling I could muster reveals that Herculite makes only tempered sliding glass doors....odd? Since I have no idea where the tank was made or how long ago, I cannot contact the manufacturer, and must assume the bottom pane is tempered at this juncture.

I decided to test the side panes to see if they were tempered as well since they are not labeled anywhere, using the easiest method I could find on the inter webs (I can provide a youtube link if anyone wants to see what I'm talking about better), I took a pair of polarized sunglasses and my cell phone, rotating the polarized lens looking at the cell phone screen with the glass in between. From what I understand, annealed glass will have no change in the darkness of the polarized lens (it will darken when rotated just as it would if there was no glass in between), and tempered glass will interfere with the darkness of the lens.

According to this test, the side panes are not tempered, and the bottom pane is also NOT tempered. So I can only conclude so far that I'm either doing this test wrong, the test is not accurate, or none of the glass is tempered... Anybody have any experience or ideas here?

Many thanks in advance!

[NOI7734]

https://www.youtube.com/watch?v=Yb9K3IGXwC0

^Testing for tempered glass video I mentioned^

[vasko2grama]

Polarised glasses method works fine, while driving in a car if you pay attention to cars driving in opposite direction you can see the tampered windshields changed colour.

[mcgyvr]

on most tanks the bottom is the only thing tempered..
most "good" overflows are drilled out the back anyways.. IF/WHEN a bottom bulkhead starts to leak you will drain the whole tank.. if drilled out the back only a few inches on the floor.

typically with the polarized sunglasses/tempered glass trick the tempered glass will show a "plaid-like/cross hatch" pattern

IMO a cell phone is too small to be used properly.. got a laptop? put it on a white page and try that.

[NOI7734]

Thanks for the quick responses! I was thinking I'd probably drill the back anyway, I'm just concerned because I'm pretty certain the bottom pane is tempered, so I want to make certain I can see a difference between the bottom and the sides, I will try the laptop in a few here and see if that's any different. In the meantime, any suggestions on sump planning for someone who understands the concepts but has never done it before? Bulkhead sizes, flow rate, etc?

[mcgyvr]

I/most will highly recommend this system.. all plumbing sized in the diagram are perfect for a 125g
http://www.beananimal.com/projects/s...ow-system.aspx

a 40B tank makes a great sump.. and petco has the $1 a gallon sale quite often so its only $40.. get some glass cut at a glass shop and silicone in some baffles.

Flowrate through sump is typically 4-5x times display size after pump head loss.. overall tank flowrate should be 10x-20x to up to 100x for "high flow" tanks/corals..
Use powerheads to get the extra flow..

[NOI7734]

Brilliant! Laptop got it spot on, side and back panes are clearly not tempered while the bottom pane clearly is, a big sigh of relief!

Also, the link you provided is exactly what I was looking for thank you very much for your help sir!

[Legalreefing]

Cool. Never heard of that trick before