Regular vs. Compact Fluorescent for plants--how much is needed?

[Ms.Bubbles]

Hi,

I'd like a planted tank with java ferns & cryptocorynes and need to choose lighting. I understand that CF lighting is brighter than regular fluorescent, so how much light do I actually need over a 10 gallon--1.5 watts per gallon of regular fluorescent or 1.5 watts per gallon of compact fluorescent (or more???)

 

[sardesign]

for plants, ideally 2+ wpg. That number is for most plants... 3+ for higher light plants. If you stay around 2, you probably won't need CO2 and lots of nutrients... however the plants do appreciate it.

 

[Ms.Bubbles]

Should I use 2 wpg of "regular" fluorescent lighting or 2 wpg of "compact fluorescent" lighting? Putting it a different way for clarity...

Is a 13 watt CF bulb better for plants that a 13 watt regular fluorescent bulb?




thanks,

 

[Jerm]

They are the same, compact flourecent lighting is used so you can cram more lighting over a smaller area. A 20 watt flourecent blub is 20 inches long while a 65 watt compact flourecent bulb can also be 20 inches long.

 

[Raithan Ellis]

Actually, there was a good thread about this on the Krib which actually relied on the LUX that bulbs put out... not sure what the link is anymore, but the general lighting section on the Krib can be found here: http://www.thekrib.com/Lights/index.html

The rough consensus was that three T-8 32w 48" lamps were equivalent to four T-12 40w 48" lamps. It's all about the efficiency of the lamps.

Now, going forward to PC lamps (T5 diameter, each numeral representing 1/8" diameter), the bulbs will be even more efficient at delivering the light, and less current will be needed to stimulate the phosphors. Without a light meter, it is difficult to say just how much of an increase there is, but I assure you they are brighter yet... and of course, this all depends on the brand of bulb and the phosphors used and other enviromental aspects (reflectors or not, ect)... (Incadescent lamps are roughly 7% efficient, Fluorescent roughly 20%, and Metal Halide/High Pressure Sodium roughly 40%) Overall, I hope this helps to give you a general idea.

Quite frankly, it's just a rule of thumb anyways... and it was based on the old T-12 lamps, I believe. You can put 3+wpg of T-12, or T-8, or even PC/T-5 lamps and still get good results with any of them without problems. Brighter never hurt anything (except your eyes and wallet), it will just require a bit more effort on your part with nutrient dosing and CO2.

Cheers!
Raithan O. Ellis

P.S. The sun is speculated to be approximately equivalent to 380,000,000,000,000,000,000,000,000 watts... yep, that's 380 followed by twenty-four 0's...

How are the plants on Earth doing? ;-)