Adhering Rock to glass barebottom

[LSU-reefer]

How does everyone secure their rock to a glass bare bottom?

I am debating goin sand versus barebottom and one of my main concerns with barebottom is the rock sliding around. Has anyone used silicon or some other adhesion on the bottom rocks to prevent movement>

 

[Dkmoo]

I think the bigger concern is the pointy parts that create uneven pressure points on the bottom and cracking it.

From what I remember, what people do typically are either sanding down and flattening the bottom so its smooth against the glass. It shouldn't slide but if you want you can then cut out a same shaped silicone matt to put under.

The other method is to make an acrylic pane with holes and glue acrylic rods into those holes to make a kind of stilt to sit the rocks on., like what I used to do. Heres a picture of a leftover rock.

 

[Cory]

The old way was putting a sheet of white hdpe or cutting board thick enough that it doesnt warp over time along the bottom 95% of the tank. I actually have this concern in my tank at the moment and have been thinking how to do it without a cutting board.