750 Watt Equivalent 5500k CFL

[bethmarie]

Am just starting to experiment with growing under supplemental light and ran across a 5500 k, 750 Watt equivalent CFL. Are these better for growing orchids... or sauteing them? That sounds like a lot of light to me.

Right now CFLs and clamp on fixtures are what I can afford. The 750 watt bulb fits the clamp-on style grow fixtures that I have, so I could use it... but don't know if I should. Presently I've got a mix of 2700K and 6500K, from 150 to 200 watts equivalent on a collection of about 15 orchids ranging from angcm to catts to phals....
Has anyone used that high a CFL wattage? Any thoughts or feedback?

[naoki]

Are you talking about 200W CFL like this?

System Comp Fluorescent 200W Day

If so, I'm not sure these clamp-on style reflector works well with it. The bulbs are pretty big, so you won't get good reflection (and waste lights). But with a proper reflector, you should be able to grow high light orchids like Catts and Angraecum.

[bethmarie]

This is the 750 watt CFL I'm referring to. I've got lower wattage CFLs in clamp on fixtures in my growing area now. I'm aiming for a balanced spectrum and plenty of light.Wondering if this one would be a useful addition or if it's too much for my small growing space.

[Susie11]

Hmm, this is interesting. I am just about to buy a 60w 6500k bulb (CFL) to use in a clamp on fixture. I hope that it is enough to get my Den. spectabile into bloom. After reading this 60w seems quite tame.

[Ray]

Don't get fooled by the "equivalent" statement. It is a 150W bulb, and that's how much light you can expect from it. That is still quite a bit of light, though.

I bought a 250W cfl and reflector from Farmtek, and now only use it as my greenhouse work light. Yes, it's bright, but not as bright as I'd hoped, and as is the case for all cfls, relatively inefficient, only capable of illuminating about a 5' square area.


One of the problems with cfl's in the first place is the spiral-, or in the bulb above, the "zig-zag" design. In a straight fluorescent tube with a decent reflector, a very large percentage of the emitted light goes directly to- or is reflected to the plants. With a cfl, a significant percentage of the light - that emitted not only to the interior of the spiral, but that emitted where the coils face each other - never gets to the plants, even if you have a good reflector to direct the rest of the light toward them.

The end result is that you plants get something on the order of a third of the emitted light. Sure, it looks bright, but "bright" is an eye thing, not an equivalent chlorophyll things

[zachkent29]

Ray,

I understand your statements about the CFL's being inefficient and that the plants receive roughly a third of the emitted light. But, how about FC measurements taken at the plant levels? Is it equal to the reading the light measure is giving me or is it lower? I just started using artificial lighting (CFL's), recently, and I've been wondering about that.

[bethmarie]

Thanks for the feedback, Ray. Given my smallish growing area, a 5' area is not too bad. Three or 4 of these and I've got catt light in my whole growing area.
I can't afford one of the hood types yet & the whole mounting issue besides is a stumbling block. It takes no handywoman skills to clamp on the clamp ons

[naoki]

Originally Posted by zachkent29

Ray,

I understand your statements about the CFL's being inefficient and that the plants receive roughly a third of the emitted light. But, how about FC measurements taken at the plant levels? Is it equal to the reading the light measure is giving me or is it lower? I just started using artificial lighting (CFL's), recently, and I've been wondering about that.

If you measure footcandle at the plant level with a light meter, it should be the light level your plants are getting (as long as your light meter is not broken). Maybe you are not asking this obvious question. By any chance, are you confused footcandle and lumen rating of the bulbs? Even if you are using a same bulb with the same lumen rating, you'll get different footcandle at the plant level if you do or don't use a good reflector (you could easily waste majority of electricity in this way). Or distance between the plants and the bulb will influence the footcandle.

[naoki]

Originally Posted by bethmarie

Thanks for the feedback, Ray. Given my smallish growing area, a 5' area is not too bad. Three or 4 of these and I've got catt light in my whole growing area.
I can't afford one of the hood types yet & the whole mounting issue besides is a stumbling block. It takes no handywoman skills to clamp on the clamp ons

Beth, you should make sure that you are looking at the long term costs. Initial cost could be trivial compared to the maintainance cost. For example, let's say you use:

4x 150W CFL = 600W (actual consumption could be different from this).
15 hours per day
Electricity: $0.21/kWh (it may be cheaper in your place)

You spend $689.85 per year.

If you are using a good reflector, you could get the same amount of light with 2 CFLs. So this means that if you spend $345 to get 2 good reflectors (in reality, it's much cheaper than this), you'll recover the cost in the first year, and you'll save money after the first year.

If you think in this way, you can easily justify spending more initially on higher efficiency system to save in a long term (well, 1 year is pretty short term, though). You also need to consider that you'll need to replace the bulbs, so the cost of bulbs should be considered, too.

[bethmarie]

Holy crap! Could I really be spending that much on CFL bulbs? I've got three in operation currently--a 40w 2700k, a 150w 6500k and a 75w Blue max daylight lamp. Running them about 12 hours a day. Not looking forward to my next electric bill. guess i was thinking the efficiency of the bulbs made them much cheaper than that, but didn't do the research. Yikes!