My little pond (4x6) has a fountain with a pump that's actually far to strong, so water splashes out and I keep having to refill the pond. Of course, I could buy a new, smaller pump, but that would be far too easy :) While thinking about that, I started looking here at various waterfalls in ponds, especially Cliff and Joann's waterfalls. I really like their low falls. So, I was inspired to try to create a little waterfall in my own pond.

I tried it out with some aquarium tubing that I had, connected to the pump with garden hose connectors, and it worked beautifully. Now I want to install it properly, without the tubing floating on the surface. I bought some firm pond tubing which can be tucked behind/under the rocks. But I'm not sure how to go about actually installing it in an existing pond without emptying the pond, which I don't really want to do.

The pond has rocks along the walls and flat stones on the edges, none of which are actually cemented in, which means that the stones are easy to move, but also that when I move one, others tend to fall down to the bottom of the pond. I'd really appreciate any advice on the easiest way to install the tubing.

Here's a photo showing the fountain splashing (the net is no longer covering the pond):

And here's a close-up of the rocks (more recent photo with different plants)

Just FYI, your pump might have a dial on it, and you could turn the spray down, or you could buy a little special clamp (I think its called a "restrictor") that allows you to clamp down the tubing, so not so much water gets through.
I have a set-up like yours. All I did was to attach the tubing to the outflow of the pump (or a side outlet) and put your pump on the opposite side of your pond as the waterfall, and just guide it along the bottom side of your pond, and then bring it up close to the waterfall.
You can hide it under rocks.
And you can hide the hose in the water by putting some plants over that area.
Just be sure you stabilize the tubing well at the waterfall. You wouldn't want it coming loose and emptying out your pond.
And just in case this would ever happen, you can put your pump on a block of some sort, so if it does drain, it will stop emptying while there is still a few inches of water for your fish.
Good luck!

Eventually, I built the prototype of the waterfall on one side, and set a small pot on the other side for water to trickle into and out down the rocks. I decided not to 'glue' the pipes in place yet, but to see how I like it first. From having a pump that was too strong for the fountain, I now think the pump could actually be stronger :) I may take out the second pipe and only have one trickle, although I actually quite like having both. And the benefit is that the stones on what was supposed to be a bog/marginal shelf but which were never covered in enough water, now get watered every day, so I can use the shelf at last. Thanks for all your help and encouragement.

Here's a little video.