Adding rocks and gravel to a pond solves many traditional pond problems. Contrary to popular opinion, adding rocks and gravel reduces pond maintenance. Gravel, unlike a smooth pond liner, provides surface area for bacteria to colonize. Fish waste and other organic matter that settles to the pond bottom gets broken down by the bacteria living there. Anaerobic sludge is therefore decreased naturally the way nature intended it to be. Additionally, covering the pond liner with gravel protects the liner from harmful UV rays and damage from animals and other sharp objects. The rocks and gravel also help hold down the liner during high ground water conditions and create areas for fish to hide when predators come around. Finally a stone bottom looks more natural and is safer to walk on than an exposed slippery rubber liner.