Kelly,

Congrats on your new pond project!

This site is mostly geared to larger "fishing" type ponds. However, there are several experts on your type of pond. (I am NOT one of them.)

1.) As regards your water source: Yes, rain water should be very good for your usage. However, if you need to supplement during a drought, then tap water should be fine - if you let the chlorine evaporate out sitting in a kiddie pool or basin. Most of the chlorine should be out after 24 hours. The last trace should essentially be out after 5 days.

2.) As regards your soil/substrate: I think starting at the least expensive end should work fine for your project. Another option for you is to sink some plastic pots in your pond filled with soil. Start your plants that you fear will spread too much in the pots. You could certainly experiment by filling a few pots with cheap soil and a few with the expensive stuff. If your plants prosper greatly in the expensive stuff, then you can determine what is the best trade-off for your pond.

3.) As regards aeration: A very shallow pond such as yours is very easy to keep aerated because all of your volume is within 20" of the air/water interface. I believe your waterfall and spitting frog should be sufficient. (Unless you do something like load the pond with a huge mass of koi.)

The only other time I could foresee a problems would be if something killed off all of your plants, or the pond was filled with leaves or fronds. Decaying organic matter in a shallow pond could use up the oxygen in the water.

Finally, I would recommend being flexible on the "evolution" of your pond. Yes - do a good plan, but your plan will almost certainly NOT be perfect. I would do the initial design under budget, and then use some of the leftover money to fix problems as they occur. For example, if varmints do end up eating some of your pond animals or plants, then you will have to observe their sneaky methods and subsequently modify your defenses.

Good luck on your project. It sounds like something that should really flourish in your part of Florida!

P.S. After you get things established, we really like successful "after" photos on the forum. (Once the photo function is repaired.)