I have posted this before, but figured I'd post again for those who missed it. I ordered this background from Designs by Nature website as well.
I installed it in an established tank with fish swimming around at the same time.....which proved to be quite difficult, but it is possible. The background floats very strongly, so if it's not glued in, it has to be secured under aquarium lip and with gravel at the bottom.
I cut a portion of the background away for the filter tube, as shown in picture. I kind of cut out too much, but oh well, it works ;)
These are awesome backgrounds, I suggest them highly.