shelgirl,
I love your new pond!
If you're not to worried about a bowl shape on top, strawberry pots make good trickle towers. I had one and I filled it with (sorry brain dead at the moment) the stuff that looks like charcoal but reddish in color that you use in propane grills. Pot already had a hole in the bottom, so I ran a hose up through the bottom and just barely stuck out the top (above) the charcoal stuff. I sat it on a three legged flower planter stand in the pond. It worked really well.
Another idea might be to buy a couple clay pots, just two different sizes (one just the next size up from the first) and the round bottom plate the same size as the bigger pot on the bottom. You would stack the larger pot on the bottom upside down, probably want to set on a stand that would accomodate that size pot, then put the
smaller pot, upside down on top of that, and finally put the saucer (upside right - of course you would have to drill a hole in the middle of this) on top of the second pot, run your hose up through the pots and there you would have it. Probably wouldn't be deep enough for plants, but could put some charcoal things in the top (same as the strawbery pot idea). Never tried that in pond, but made a really cute birdbath out of two pots and the base of the larger one, was pretty cool.
Sorry if this is clear as mud, but hard to explain sometimes.
Good luck whatever you decide!