DIY Cube tank plans..

[new but handy]

#1 is the stronger way (apparently, although I have no idea why)
also make sure you account for the thickness of the glass on both sides of the tank. I noticed you accounted for the glass on only one side.
IE
22x22 -1
18x22 -2
18x21 1/2 -2


21 1/2 not 3/4
Make sure you clean the glass with acetone very well and you shouldn't have any problems.
Use pieces of duct tape to hold the glass together while the silicone cures