Thanks...
Since I'll already be buying 2 large tubs, should I put as much of the previous water I can carry or are you saying it really doesn't matter either way?
Doesn't matter.
Also, I'm not a huge fan of the light-colored sand in the tank...When I get around to replacing it with a darker or brighter color, will the bacteria on the rocks and filter media be enough to maintain the balance?
Once the tank is cycled it shouldn't be any problem to siphon out the sand & replace it with another color of sand, there should still be plenty of bacteria colonies established in the tank if you wait a week or so before swapping out the sand, oh btw I highly recommend Python siphons, they make doing water changes & vacuuming sand/gravel so much easier & way less time consuming - they are worth every penny.
Dang, I had another question, but I had to do something and lost my train of thought...I'll have it in a second.
No problem, if you think of anything else feel free to ask.