The part you are suggesting. When I dug the hole, I laid the liner right up to the bricks/retaining wall. I doubt there is any room for pebbles. I may be able to stack some bricks or find something to cover it up, but it not bothering me right now. I had to use some of the extra bricks on top of the retaining wall to help boost up the top waterfall piece. Which I wasn't planning on buying. Because the pump I bought didn't come with a hose, so I had to buy some additional pieces. Sometime later today, I'm going back to the home improvement store and buy some extra bricks and a couple other things for it. I'll probably add things to the pond and waterfall to hide things better as I go along. But for now I'm glad this project is finally over and my next backyard project later this year is to plant a tree. To produce some extra shade for the yard and house.