Is it ok for rocks to be placed all the way to the back of the aquarium glass (touching) or should there be a gap for circullation?

I don't think there needs to be a gap for circulation, but I like a little room for fish to swim behind, plus I don't want rocks putting pressure on the sides of the tank or scratching it.

I agree with Yodahorn!

I also like to leave just enough room to get my gravel vacuum
between the rocks and the glass!

Geelite, Klaus (buntbarsch) posted a link to his site on another question about rocks that I think is very helpful.

Take a look here: http://www.buntbarsch.ca/index_files/Page704.htm

Thank you Aura, dont know how i forgot about that link, i had a peak at that when i first joined this site dumb dumb

Geelite, I usually don't leave a gap. However, since I like to use the largest rocks that I can fit in the tank, I make sure that they are not leaned against the glass either. The weight of these large rocks would put too much strain on the silicon that holds the tank together. Small rocks you can lean against the glass without any problem.

Good luck and show us a picture Good Job