bhammer, I think everyone is poking at a single 500W bulb here. There's several factors to look at. Plus, I'm not even aware that there is a 500W system out there. I know about 400W, and I know about 1000W, but never heard of a 500, but that could be just me.
500W is probably a good choice for your tank, IMO
. However, MH
bulbs only put out so much of a footprint, so in order to cover your tank you'll probably want to split it between 2 bulbs, meaning you have 2 250W bulbs to create the 500W of total light you're after. Like Larry said, 175s could work as well depending on your bulb choice.
As for needing supplements, I think that's really personal preference. Bluer (higher K
bulbs have the blue color spectrums within them, so it's not necessary to have any supplementation, just many people prefer to have it as well so they can create a dusk-to-dawn effect by having the actinics on first for a little while, then the MH
, then reverse the order when shutting down for the day.