90 gal... Best bang for the buck?

Hi gang,

It's been smooth sailing with my Clown Loaches (CL's) and other
fishies... As always I'm looking towards the next upgrade after the new
year or later... A few questions please:

Q: is a 90 gal. tank the best "bang for the buck" as a step up from a
55? 110 gal better? I've alway thought 55's to be best deal per gallon
(bang for the buck) as compared to the smaller tanks. I'd be putting my
6 CL's and one queen botia dario. They are not that big yet (about the
size of my big thumb) but if I can find a used 90 gal or so I'd do it
before they are too big for the 55....

Q: Is a 90 gal a "common" size that should be easy to find locally
used? 110 better for almost same price? I don't know about those big
tanks but I have the space and I want loaches the would be too big for
a single meal each... Not the I would actually eat them, but I like 'em
big... BIG!!! I have the space and a good solid floor on a conrete
slab.

Q: Where is a good simple site to compare tank size in gallons along
with dimentions.

At risk of rambling too much I'll cut it short now, Thanks fine group.
Karl.