CFL bulb wattage question

southpaw

southpaw

Lefty
Jun 7, 2007
720
0
0
55
Tennessee
I was wondering what wattage numbers you should really go by on the CFL bulb package.... I bought 2 10w daylight bulbs to put in the hood of a 10g I have to try my hand at a low-light planted tank. I got the 10w ones as they were smaller and would screw into my hood easier than some of the larger 13w ones I saw. Plus all the 13w ones they had werent the Daylight 6500k ones like the 10w were.

On the package the bulbs say 10 Watt = 40 Watt ...... So would this mean I am getting 20w of light with 2 bulbs or 80w of light ??? From all the threads I have read everyone is basing it on the 10w number even though I thought the 10w meant that it only used 10w compared to the 40w a regular bulb would use to save energy yet it put out as much light as a 40w.

Might be a simple answer to this but I figured I would ask to get it all straight in my head incase I decide to convert the hood on my 55g for a planted tank by installing screw in bases and CFL bulbs.
 
^^Yep....its just comparable to 40w of incandescent lighting.
 
Thanks for the replies....I knew it had to be a easy answer :)

It is just sorta confusing by what the package says and what wattage they actually are
 
Its kinda not fair that they advertise that way, huh? Well, at least you can look at it this way... at least you have 20 watts of good lighting, rather than having 80 watts of crap lighting. Sounds crazy that 20 > 80 in this instance... but the CFL bulbs will not fail you. :-)
 
The real wattage is the lower number. We use this mostly because its fluorescent lighting 95% of what everyone uses so the wattage correlates roughly to the light we would expect since most fluorescent lights give similar light output. If everyone on the forums were using incandescent then it would be the other number we would be interested in knowing. The watts isnt light, just a reference that happens to roughly apply since most everyone uses fluorescents.

I made it more confusing didnt I. lol.
 
so if i had a 40 watt incandesent bulb, i would still have 40 watts? but if i had a 10 watt cf that was comparable to a 40 watt, i would only have 10? i think i got it now.
 
williedee said:
so if i had a 40 watt incandesent bulb, i would still have 40 watts? but if i had a 10 watt cf that was comparable to a 40 watt, i would only have 10? i think i got it now.
Click to expand...

a 10w cf would give off equal to greater amount of light as a 40w incandescent thats all that means. just the incandescent needs more power to operate, and most of that power will be given off as heat
 
Yeah its kind of weird to understand at first. We are trying to correlate wattage to light, and since in this context wattage isnt light, think of it like there is a conversion factor between the different kind of lights, with a standard fluorescent bulb being 1:1. Meaning 15W fluorescent = 15W of light. But incandescent is really inefficient, a 15W fluoro puts out as much light as a 60W incand so an incand has a 1:4 ratio. It would take 4 times as much wattage to equal the equivalent light of a fluoro. And your stuck with really low color temperature (yellowish light). So for something along the lines of a 55G tank which you would have around 110W-220W typically, you'd need an incandescent of 440W-880W. Thats going to be horribly inefficient and cost a lot more on the electric bill, and heat your tank up considerably since it will throw off a lot of heat. Halogen efficiency is slightly better but still less than half of a good fluoro.
 
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