Well I just received my new crevice background from universal rocks and it looks awesome! I can't wait to get it installed. This is a new 110 gallon setup and I'll be running an FX6 which I'd like to hide the intake and the heater behind the background. I was planning on siliconing the background 1 1/2"-2" away from the back glass. I will be using Caribsea Cichlid sand also.
Should I cut 1 larger hole in the background and silicone mesh to protect the fish from going behind the background? If so how big and where?
Or should I drill multiple small holes under rock ledges so they are not seen? Again if so how many and of what size?
I'm worried that if I make too many small holes or too large of a single hole the water draw wouldn't be strong enough to pull in floating debris. On the other hand if there are too few small holes or too small single hole, I don't want the filter to suck all the water out from behind the BG faster than it can refill. Anyone have any input?

Here is the background

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