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Re: Light bulb advice

> I have trouble understanding this statement. CFs are T-5 and T-8s will
> *always* be a bit less efficient, AFAIK. Their absolute brightness is *way*
> lower than most PCs. The reflector design can get you part way back, but
> only if it is clever and terribly efficient. 
> > 
> > The other problem with T8s when compared to PCs is that they are designed to
> > work at 25 degrees C. while T5 lamps are designed to work at 35 degrees C.
> > Most aquarium hoods are going to be closer to 35 rather than 25 degrees C.
> > On the other hand T8s are somewhat more efficient than PCs to begin with and
> > last longer as well so the T8s should be cheaper to operate.
> I have little sympathy for those who would design hoods with insufficient
> ventilation.
> Most fluorescents have the same negative response to heat. The T-5s just
> *have* to put up with more. They aren't exactly "designed" to.
> My 40W PC is rated at 20,000 hours. I haven't seen many T-8s rated for that
> lifetime.

Don't be disrespecting T8 lamps.  They *are* more efficient than compact T5's; typical T8's with "80" series phosphors are about 95 lumens per watt, and some go as high as 105 lpw.  T5 compact fluorescents approach 90 lpw, but I've never seen any that were rated higher than 86 lpw.  40W compacts are rated 20000 hrs, but most other wattages are rated 12000 - 16000 hours (still pretty damn good).  T8 lamps are rated 20000 hours, and some are rated 22000+.  T5's are brighter because they have less surface area than T8's.  T8's are a lot cheaper, and last marginally longer.

I use T5 compact fluorescents for aquarium lighting because I want to pack lots of light into small space, and because my aquariums are all less than 4 feet long. I use T8 lamps for general lighting because they are cheaper and more efficient.  If I had a 4 foot tank, I would try very hard to use T8 lights.  I think 2 F32T8-SPX50 (or the Philips equivalent that is a little brighter) lamps with a Motorola high light ballast and a decent reflector ought to be plenty of light for a 55 gallon tank.

BTW, does anyone know if they make a "grolux" type lamp as a F32T8?

Best regards,