MacFan

It would probably be ok. I know the florescent won't penetrate as deep into the tank. But if you wanted to mix color temperatures in lighting, that's how you could do it. Do like a 10k MH and 5k T9's. Or vise versa... if it were me, I'd probably just go with a 250watt MH, but I don't have experience with combination lighting to know the pros and cons of it.

As far as using a canister filter with an overflow, I am doing it on a 72g bowfront I have. It is possible, but it can be tricky. I've never used a sump, I've considered it, but I'm all about plant tanks and it will dissipate CO2 from the water. I've heard of people who create pressurized sumps to cut down on this, but at that point you're basically at a canister filter. With a sump, you're basically using the pump to push water up into the tank. When the water rises above the overflow intake, it runs over the overflow and out through the opening in the bottom. It is good at skimming the surface because of this action. If the water level isn't high enough to flow over, nothing bad happens.

When you use a canister filter, as erock noted, you can't allow it to take in air regularly if you want it to work properly. This means having the water level in the tank high enough that it's always flowing over the edge. Obviously if the water level is high enough, the overflow box will fill with water to the same level. There is nothing wrong with this and it will work just fine, however you lose that skimming action. It is possible to get the skimming action by getting the water to exactly the right level where the overflow box is maybe 50% full and the rate the water is flowing into it matches the rate the pump is pumping water back into the tank. Getting there isn't difficult, it's maintaining it that is difficult. Evaporation will take that level down, overfilling the tank will bring it up too high, floating plant matter may block the intake and let the level drop, etc. If you used an auto-fill system and were willing to accept that it might not skim 100% of the time due to periods where the water level might be too high, it would be fine. Or if you didn't obsess about it skimming as I finally resolved to, and just fill it high enough, then it's fine. It's a convenient place to hide the heater but remember that you need to keep the water covering the heater when the heater is on. When you do water changes, be sure to turn the filter off as once the tank level drops below the overflow the pump will pump the overflow dry. I got one of those remote switches they sell for lamps, it's basically a switch at the end of a cord and at the end is a plug you plug your lamp/filter into and then plug that into the wall. So I can switch off the pump when doing water changes without crawling under the tank to unplug it. Make sure the switch is rated for the power consumption of whatever you plug into it if you choose to go that route.

Michael