FOLLOW UP: Not sure, at this point that the turtles are 100% pleased with their new addition. See above post [#19]. Have yet to see anyone in the water on his/her own -- still have to put them in. Again, certain it's the issue of "cover" for them. For the most part they seem fine once in the water -- it's the getting to & from that spooks them. There is roughly 3-4 feet where the liner is covered with either my faux rock ramp or rocks covering the liner. In their eyes, since they're still young & small, that open space makes them vulnerable! I planted along the edge, but those plants just aren't growing fast enough, so got some mandevllia (sp?) vines and a super huge fern (that actually tolerates 4-6 hours of sunlight!) to see if that would help. Have the vines stretched out as close to the water as possible and will make a little over-head trellis for it. Looks promising. There is plenty of water lettuce and parrots feather in the water for cover.
They are fun to watch when they're in the water. I'll start out by placing one on a rock in the shallows. Some will immediately scramble around, and end up in "the deep end," swim around and float, and hide among the water lettuce, then first chance, will get out. One or two will start rooting around, ducking head under water, then maybe swim a little bit. A couple will head for the perimeter areas [they can partially see out] and act like they're looking for an escape route. I bought some "aquatic turtle treats," and will float one next to anyone who is in the water hoping to give them a pleasant experience. If I forget the treat, there are a couple of the turts that will climb out of the water and come over to me and look up at me, "Mommy, you got some food for me?" The ones that are more relaxed seem to enjoy being in the water, but I guess the others are just too scared of getting eaten.
Oh, and I did end up "diving" the other day. LOL! I got son to go outside with me and be my spotter while I donned mask & snorkle. There was 0% vis! I couldn't see a thing until it hit my mask -- had to feel around for the pot I dropped. I was having fun -- makes me long for a SCUBA trip.......sigh!