Mark Stone wrote:


All else being the same, I would go with the four foot -- as a rule of
thumb, the larger the aquarium (to a point), the easier the
maintenance! --Mark

I once helped with the maintainance of a commercial show-aquarium,
because at a depth of 8 m (20 ft or so) the owners relied on the local
scuba community to do the work for them. In exchange we had the
opportunity to dive in several million l of filtered, crystal-clear sea
water, brightly illuminated and with plenty of exotic species (including
a pack of 4 sand tiger sharks), with air provided at no cost.

So maintainance can be quite easy, even for LARGE tanks ;-)