22's and liners are not a good pairing. Several years ago I was going to pop a raccoon that was obviously sick with distemper that was rooting around in the old, much smaller pond. I almost pulled the trigger until I thought a little harder about where the 22 magnum was going to go after finishing the job.
I waited until a better position.
I just ordered a pond bubbler rated for the outdoors that wont turn the pond into a boiling cauldron of fish and debris. It is hard to nail down the compromise between appearance and effectiveness.
I would love to have a waterfall, but fearful of water loss from evaporation, wind, and splashing. I have to keep this thing topped off with a well, and our well isn't exactly the most productive when drilled on top of a rather large hill. A bubbler is one of the most efficient ways to move water from bottom to top, and is lily friendly. Lilies HATE swift moving water.
I am planning on getting some bags of play sand, even though I could raid an unused play sandbox. I just don't want to introduce several years of organic crud accumulation, and it may piss off the sand bees that have taken up residence. Those things are faster than I can run. The sand needs to be added to increase the under-gravel filter effectiveness. The white pool filter sand would just look obnoxious.
