I'd like to go with sand. I'm concerned about the possibility of gas
buildup, however. Thoughts?

Flourite or Onyx would be easier, especially if you're a beginner. But lots of
people use plain old sand in planted tanks. Pool filter sand is a good,
low-cost choice. Mix laterite into the bottom inch or so. (Be careful not to
use coral sand or anything like that. It's okay for marine tanks, but will
play hell with your pH in freshwater.)

Sand can be a problem in an unplanted tank, because it tends to compact and can
be hard to vaccuum (since it's so fine). But with a healthy planted tank, the
plants' roots will bring enough oxygen into the substrate to keep it from going
bad.

Also, best filter for a 40 gal moderately planted tank? Canister-type is
what I'm leaning to, due to space considerations, HOT design would move the
tank out too far.

A cannister is ideal for a planted tank of this size. It gives you control
over the amount of surface turbulence, which can be important if you decide to
inject CO2.


Leigh

http://www.fortunecity.com/lavender/halloween/881/