I just got the bottom 1/2 o the background in. You can't see that 5/8" inlet at all unless you are on the floor looking up. Note the gap at the bottom. The background was a bit short for the tank but the price was right. I'm doing almost an 1/2" of Fluorite, and another 1"-2" of pool sand and Aragonite. Then from front to back it will get a bit thicker to simulate some dept as well as have the rocks piled up. I'm filling up most of the back portion with 2" of the older gravel I have.
I'm also soaking the rocks I grabbed so I can start scrubbing them good. The look really red right now. The lighting in the house and outside was totally different and the rocks have some redish clay/mud on them from the soil up there.