Diana
Since you live in Van why don't you stop by the Aquarium
in a off time (early am) and see if you can't speak to who ever looks after the aquariums cold water system
I talked to one of the aquariums' staff a couple months ago in terms of general outlines they were most helpful, they told me that due to slower metabolism rates they are, temp aside, easier to maintain than tropical systems
I hope thats true
Good luck (I think its a great idea by the by)
Cheers
Mitch