I built a cave for my L-25 pleco. I used 18 inches of 6 inch pvc covered in rocks using pvc glue (cement). Allowed to cure 24 plus hours.Set in bucket with garden hose on high to wash of anything that was not stuck on. Placed in tank. I tried using silicon glue but over time it would come off.
Also I sanded the pipe for better glue adhesion prior to using any glue.



