Regarding the curtain effect waterfall. I have read that a straight,smooth,continuous edge - possibly rounded - is what you need, as opposed to rocks arranged there. If you need the water to clear the edge a little bit before it goes over and in to the pond, I would use some kind of pipe, set horizontally, as an edge, with liner over the leading curve. Does that make sense? Have you built any of this, yet? It may be hard to retrofit the liner for this. It probably needs to be all one piece, so as not to get water under the edge of the liner if you have to add some to cover the pipe. Also, I think it would be best to have that part of the liner extend way down towards the pond surface so it doesn't splash over the pond edge behind or under that area.

You also need a good quantity of water backed up behind the edge for it to really make a good "sheet" of water.

Hope this is helpful.

Ann