Can you run only 3 lights on a 4 bulb T5 fixture?

[nsgrkg]

I have found a Nova Extreme 4X24 fixture with lunar lights for 151.99 (free shipping ;-). I need more light than a 2 bulb fixture provides, but less than 4, as using all 4 would require CO2 (I have a 54 gallon tank). I would like to incorporate CO2 later, but because of the expense (and my budget) I would like to build my planted tank gradually. Buying a 4 light fixture would allow me the flexibiltiy of adding additional light and CO2 later. Also, since T5 bulbs run cooler (there is a cooling fan on this fixture), can the fixture be placed directly onto the glass top of my aquarium? My tank is in a family room and using the legs on the fixture (besides being a challenge because of the shape of the tank) would cast a glare into our eyes when sitting in the den (my tank stands >4 ft. tall).

[kid creole]

Yes, but it needs to be the right bulb. Disconnect one of the bulbs. The return path of the bulbs may go from bulb to bulb, so if it turns off more than one bulb, try the next. Just play with it. The only tricky part is they get hot while you mess with them. lol

[dbosman@msu.edu]

Congratulations on the great find on price.
You should be able to leave one bulb out. Electronic ballasts can run one or two bulbs. By the way, cooler is relative. T5s run cooler than PC bulbs, but HOT5 fixtures can get very warm. Very warm as uncomfortable to keep your hand on it. You can put it on a glass top, but not an acrylic as it would sag. As to glare, if it comes with legs, try them. You might get a pleasant surprise.

[davocean]

Actually on the current units there is one ballast per pair, and they are meant to be run both bulbs for sequence.
I've had one bulb go out shutting off power to both.
On the plus side it sounds like you found an older unit if it comes w/ moons, and these have a much quieter fan as well.
I've had both, and very much prefer the older version even though it has a single reflector, as opposed to the molded reflectors on newer versions.
Plus the moons are real nice.
I'd get it, run 2 bulbs until you get C02, or go w/ all 4 maybe on a shorter light cycle.

[Hoppy]

The ideal fix, if you can do DIY and enjoy it, is to make a box enclosure for the fixture, that has sides long enough to block the light spillover that bothers people sitting in the room. You have to be careful to allow the light to cool off, adding vents where needed, but it isn't a difficult project. Then you can hang the fixture far enough above the tank to get the lower light you want, and better uniformity of lighting as well.