Hello wanted to get some advise on my 650 gal koi and gold fish pond. It there a way to keep the rocks and stones clean? The bottom of my pond is covered with a very thin layer of I guess muddy stuff. I would love to keep it to where I can see the the different colors of the rock and stone. Not sure if that is possible. Also my water fall is the same way. I have a skimmer opposite of the water fall. Thanks in advance