Hi, I'm looking to build two new vivariums, a 16"x16"x26", ~29 gal, and a 12"x12"x20", ~12 gal, for Gray Treefrogs, possible White's down the road (not mixed!). I was originally planning on just the big one, but I figure it's stupid to build one tank when I could build two. Both will be vertical tanks, built out of 3/16" glass. I can (and already have) cut the glass, but don't have the tools/know-how to drill holes in it. These are my first viv's that will have more than a couple hours put into them, so a few questions while I'm still in the gathering materials/planning stages:

1. How much ventilation? 16"x16" on top enough for the big one? Or would 6"x16" in the front at the top be enough? I was thinking eggcrate lined with screen mesh on the top or just screen mesh on the front? A top opening has to be able to hold ~15lb worth of cats.

2. I plan on a front opening door, and was looking at acrylic piano hinges, which can be glued right on the glass without any hole drilling. Any other suggestions? Anyone know a good source for the hinges that has reasonable shipping to Canada?

3. I'm going for a waterfall with a maybe 8" diameter, 1-2" deep pond at the bottom for the big tank. I planned on building it out of Quikcrete and the Acryllic sealer over styrofoam blocks. I understand I'll need to soak this in something acidic (vinegar) for a few weeks after it cures to keep it from raising the pH of the water. I was going to tint the quickcrete with different amounts of black, water-based paint for the many thin layers I plan to apply. Is this a solid construction plan?

(This is also why I decided to build a smaller tank at the same time- impatience. I expect the waterfall to add 6-8 weeks worth of curing and soaking, and I'd like to get a new tank done before the end of summer!)

4. There will be an ~3/4" hole in piece of glass set aside for the bottom of the large tank (it's glass from old slider windows, this is where a handle was). I'm planning to build a false bottom and use this hole for drainage. Then a small tank/filter outside, pumped to the top of the waterfall (same sized hole at the back about 20" up). I figure this way I can let the waterfall/pool run wild and should still be able to clean out the pump/filer when cat hair miraculously finds its way in through tiny openings in the cage. Any problems with this?

5. Backgrounds of expanding foam, covered with clear silicone, covered with coco-fibre/peat moss, anything else? I'm (irrationally?) afraid of GE silicone II, and this clear stuff is the only kind I can find that claims to be aquarium safe (Home Hardware's 'house' brand). Any other options for covering the foam?

6. I'm going to be embedding some tree roots from our yard in the background (it's from a cattle farm, no spraying has happened here for many, many years, if ever). I was thinking linseed oil to help preserve the wood? I also have some grapevines that I will be putting in, linseed as well?

7. How about some of the fungus/mushrooms, the kind that grow on the side of trees? I like their look, and they would make good perches on the background. Anything I should be concerned with and any tips for preserving them?

Anyhow, thanks for reading, and thanks in advance for any wisdom anyone can send my way.