Are you intending to show us a picture of bacteria? Or do you mean algae? It's hard to tell from the photo exactly what we're looking at.

In the picture I'm showing is the rocks on the bottom of my cascade. I've done several algae treatments and nothing's happened, so I figure it's something else.

That is just a part of the biology of the pond. Everything gets covered with a fine algae growth and the fish nibble on it or there is a fine silt on the bottom from dirt settling out of the water. Your water seems very clear.

Yes it is pretty clear, I just want to some what keep the algae away. I guess shade would help a lot.

Shade would not help that much it would still grow--just a sign of a healthy pond. Any critters that move in need it to sustain life--tadpoles, dragonfly larva feed off whatever feeds on algae and on down the food chain.

The only way to have a pristine water feature, like a public fountain, would be treated with harsh chemicals to eliminate anything alive in the water.

I prefer a little algae, dirt and critters. Even string algae is gratefully and enthusiastically gobbled up by the fish kids.

I'm also losing water not enough to warrant a hole in the liner but enough to raise suspicion.