I am toying with the idea of retiring my 120l for now, and setting up a 120cm rimless, braceless tank , and was wondering about the additional cost of going for higher clarity glass. I already have a second hand (therefore, cheap) opti white high clarity 60cm which is a quality item. The glass thickness is 5mm on the 60cm, as opposed to 8mm on the 120cm, so I am thinking the opti white will be even more beneficial at this glass thickness. Does anyone have any thoughts on this and the extra Â£160 for the higher clarity glass? Secondly, if there is anyone out there with an unbraced 120cm, is there any significant bowing of the glass at the front? Dave.