Maximum distance CFLs can be from plants?

[Mr_Micro]

Okay guys, hopefully this isn't a dumb question but I've been looking around quite a bit and I can't seem to get one definitive answer for this question. Therefore I thought I'd make a thread for it!

But before we get to the big question, heres a little backround information on the setup this question will apply to.

Basicly, heres my situation... I've been growing in a 20" tall PC case with a 50 watt HPS light and SWC hydro. My results have been pretty good so far but I'd really like to supplement with a bit more light, especially more in the blue spectrum for for early vegetative growth. I've been getting some really stretchy plants during the first few weeks of growth and I'm thinking a bit more blue light would really help keep them more compact (which is really important in my setup).

And before anyone suggests this, I have already tried putting a remote ballasted 70 watt HPS with a tempered glass heatsheild and 80 cfm exhaust system (just for the bulb) in my case and it still turned it into a freakin oven with 95*F temps. Because of this I switched back to using the 50 watt HPS just to keep temps reasonable and maximize available space in my case.

So now, as I said before, I'm stuck with a 50 watt HPS and needing a little boost in my light output without adding much more heat to my case. So given the very low heat output of CFLs, they seemed like the perfect choice for some extra watts. In the space I have availble, I'd be able to add one CFL up to 7" long and 3" wide.


And heres where we come to the real point of this thread...

The only place in my cab I'd be able to fit the CFL is at the same height as my 50 watt HPS. Believe it or not, but my 50 watt HPS puts out enough heat that I'm always keeping my plants about 5 or 6 inches away from it to be on the safe side. Except for in mid to late flowering, when the plants sometimes get around 2" or so away from the light, but never closer than 2" away. So what I'd like to know is would it be worth it to add in a CFL light if it was always 6 inches or so away from my plants?

Also, I read a while back in the OG growfaq that the Energy Star rated "Energy Saving" CFLs can be placed much farther away from the plants than normal CFLs due to their greater penetrative ability. Does anyone else have any experiance with this or know if theres any truth to this?

And finally, how much heat do you think a single 26 watt or 42 watt CFL would add in a box thats 17" long, 8" wide, and 20" tall? If my internal temps are averaging around 83 to 88*F right now (about 6 to 8* above ambient room temp), would I be able to add in a 42 watt CFL without any signifigant difference? Or would I have to use a 26 watt instead?



Anyway, thanks for reading this long ass post and hopefully someone can shed some light on some of these questions.

 

[THE MUFFIN MAN]

If i remember correctly, most grow lights ( HPS,MH) stop penetrating after 3 feet.
(obviously the light doesn't stop dead in its tracks but... you know what i mean!)
I would think that CFL's should be treated the same as Fluoro's and have them as close as possible for maximum lighting.
Is there a way to side mount your CFL to have them closer tot he plants and not be in the way?

 

[darrinjefferson]

you can and should keep your fluoros as close as you can to you plants. usually this is around a few inches. because they are a weaker bulb the light and lumenens dont penetrate very far.

heres a look at my cab


i got those light about 4in above my plants.

late

 

[Mr_Micro]

Thanks for the advice guys!

I've looked at my PC cab again and again and still concluded that the only place I could really mount a CFL would be about 4 to 6 inches away from the plants at all times.

Another thing I was kinda curious about was that I know with HID lights the higher wattage the bulb is the more penetrating power it will have. Would this apply to CFLs as well? Would a 42 watt CFL have more penetrating power than a 26 watt one? Up to this point I've only used HPS lights so this whole CFL thing is a bit new to me.

I was taking a look at Red Greenery's rubbermaid setup not too long ago and it looks like his 42 watt CFL bulbs would have to have been at least 6 or 7 inches away from the plants during the early and middle stages of growth.

I suppose ultimately I'm just going to have to try putting in a CFL and see if it makes any real difference in growth and then go from there. Gonna pick up a two 26 watt bulbs and two 42 watt bulbs (two 2700k temp, the other two in the 6400k range) for veg. and flowering and see what difference they make. I'll use the 42 watt CFLs if they don't raise my heat level too much, otherwise I'll stick with the 26 watt'ers.

 

[stickyickyicky]

RED also has a window between his lights and his plants. he also said that he uses cardboard boxes to raise his plants up and down. i am not sure how far up or down but you get my drift. From what i have been reading the closer you get those CFL's to the plant the better obviously not touching but within a inch or so.