One thing to consider: over time, you will accumulate "mulm." It is this insubstantial, soft, crumbly strange stuff - part of the by-products of everything being broken down in the natural cycle of a pond. It settles to the bottom and looks like a crumbly carpet -- it's easy to see the fish against -- although the juvenile goldfish are dark, so they are camouflaged. I had a few leaves that fell to the bottom, on top of the mulm. I decided to net some of it up. When the water drains out of it, what looks like a net-full becomes next to nothing! I also disturbed Mr. Beefy -- our large green frog who has taken up residence! I emptied the net next to the pond and about twenty teeny young salamanders did a slip and slide back into the pond!!!!!