hdtran":2uhlewlj said:
James,
Even if the entire tank is out of acrylic (no differential expansion in the tank itself), shouldn't you worry about the wall that the tank is set in? E.g. shouldn't you leave about 1/8 to 1/4" gap around the tank, so the tank can grow and shrink without hitting the framing?
I figured that would be a given as you wouldn't want to try and stick this into a zero tolerance hole in the wll
but yes, you'd want to have a rather large bead of sealant or thick foam gasket material to prevent gas exchange (read AC/heat loss) between house and outdoors. There are several varieties available at hardware stores up to 1/2" thick which would work well for this.
I like the plate glass window to the exterior, suitably puttied in, and a tank just inside the plate glass window. Now, you have to worry about the greenhouse effect in that airgap, but you can tint the plate glass window with a 3M film (say neutral gray).
While I won't argue with ya, I'm always leary of glass tanks (even if just a window) that size. If I were to undertake this project, I'd use a fiberglass tank with open (removeable) top and an acrylic window like public aquariums do.
Relatively cheap, structurally sound, weatherproof, proven design, and just plain neato
W. facing in SoCal is very sunny, so I'd go as far as the 50% gray film.
If using a removeable top, this can be experimented and played with, if a fairly decent chiller was used, you'd be able to play with different gels without costing too much. A Lexan top with gel would be essentially weatherproof, lightweight for maintenance, and not gonna break when leaned against the house for playtime.
BTW, being in SoCal, you've got one of the best fiberglass tank mfrs (as well as real nice guy) in the world just down the road
James