Water vs glass?

[imusuallyuseless]

I used this concept when I turned my 55G into a 180G a few years back. I would most certainly stick w/the original height instead of trying to gain extra volume by using extended frame on the front. Extra frame on the bottom will prevent you from viewing what your fish are doing in some instances(I considered this when doing my build, but decided it wouldn't bother me, turns out it did). The extra frame on top will add more water pressure if you decide to try and fill above the glass level. In any case I wish you luck and hope to see a build soon. Also the sketch you did looks pretty good, my only question being if your tank currently only has a brace in the middle or does it have two?

And just FYI the tank I built used 1/4" thick tempered glass, not the 3/8" thick glass that older 55G tanks have.

 

[liontammer]

it isent ether it is the surface area that the water contacts. because it is the pushing force of the water, that is y the port holes on a sub are so small thay can withstand more presser with the less surface area. so as long as the glass is supported on all four edges as well as the front and back from bowing you can make that tank as deep as you want with out to much worry. as long as your front support for the tank docent bow and the glass supports are on the front so the water pushes the glass into them. i have built some tanks as well as designed them. the glass thickness on a 125 should be good.