adriennemb, mortar on the bottom of the pond would hold up as long as anywhere else assuming your pond doesn't freeze solid. Cement isn't affected by cold temps, only ice. It doesn't release chemicals at least at any levels any reasonable person would be concerned about. In a freezing climate you do have to design for the top foot or so, the depth you expect ice. You have all the normal options, bare liner, dry stacked rock, etc. It you want to cover the liner my suggestion is to make cap rocks out of mortar. These can be flipped out of the pond in the fall if you like or left in the pond. Since they just hang there any ice behind them push them up a bit but no harm. The premixed mortars of today don't really fail, at least in our lifetimes. If you kept your pond in the acid range, say 6 pH or less, the acid would attack the cement and slowly dissolve it. Cement makes a poor pH buffer so you probably wouldn't be able to measure any raise in pH using normal pH tests. And in 6 pH and less the life of the mortar would be reduced to maybe the 20 to 30 year range. If the pond is in the 8 pH and above range there is very little affect on cement and you can expect it to last in the 50 to 100 year range. I got this info from studies of concrete water and sewer pipes. Here's a link to my web page on effects of cement in a pond.

I am thinking it needs much more sun.... even in my arid conditions it needs some sun.

In the pretty plate, definitely go for clear cello to show it off. The way they wrap gift baskets. I've done scads of them, though not pies, and they always sell well for the pretty factor. The trick is to be generous with the cello, and gather it at least a foot, more is better, above the pie, so that the buyer can see the pie and the pretty dish, instead of just folds of cello. You can also stick a clear plastic plate to the bottom of the pie to push the sides of the cello out a little. Make a pretty decor with coordinating ribbon and something cute like a plastic or papier mache fruit matching the flavor of the pie, or an ornament sized rolling pin or wooden spoon, or something like that. Just make sure to use appetizing colors. Reds, especially, are good, and yellows. Think McDonald's. :) You may not be a calligrapher, but your computer is! If you can't print right on the tag, just print on regular paper and emboss it on the back with the handle end of a spoon or something similar. Then you can color the front. But given that you have an infant, you could just print it out, and cut out the tag shape minus 1/8 - 1/4 inch, center it, and glue it on. It'll still look nice and be a lot less bother. :)

This is great! Thanks so much for a very interesting site.