How much deflection or bow?

[juststartingout]

How much "bow" does the front viewing area of your 8 foot long acrylic tank have?

I had just taken a 4 foot level at about a 45degree angle from bottom to top, center of tank, I was surprised to see what I would call a significant amount of bow to the front viewing pane. I measured 1/4" to 3/8".

 

[sfsuphysics]

Well when I got "creative" (read stupid) and cut the brace out of my 6' long 100g tank, it bowed out 1/8" more than it was (of course this doesn't measure the total deflection, simply the change), and that 1/8" was enough to cause the bracing on the top (which was doubled in thickness before the chopping) , to fail and crack straight through after a while