PL-L light bulb coverage area

[iamoni]

Hi guys! I was hoping you can help me in this little question.
The lumens per square foot requirement for vegging is 3000 lumens, am I right? (please correct me if I'm wrong)
So If I have a 2sq ft growing space, I will be going to illuminate EACH sq ft with 3000 lm.
I'm interested in using PL-L lamps, specifically these 55 watt lamps that give off 4800 lm which should be more than enough. This bulb is 21.1 inches long. Three inches short of the length of the growing area.If I were to lay the lamp along the length of the growing area, , it looks as if one bulb is enough to light my vegetation chamber.
Am I thinking wrong guys? At first I thought that 2 sqft of area will mean about 6000 lumens so 3000lm/sq.ft. But with these lay out, the bulb is physically covering the entire growing field. Does this mean that one bulb is enough? Or should I go for 6000lm?

 

[rives]

I don't think that I've ever seen a lumen requirement for vegging, but a 55w PL-L will easily handle the space that you have.

 

[iamoni]

thanks for the reply but how can you tell?

 

[rives]

I've been using PL-Ls for years. My mom/veg cabinet is roughly 20"x 30", and I have (2) 55w lamps in it. It works great.

 

[qupee]

Are you using a reflector of any kind above the bulb? I personally think 1x55w is a little slim for 1'x2', but it really depends how big you want them to get under it. Adding a second pl-l doesn't cost much in parts, heat load, or watt-hours so I lean towards more but if you're aiming for minimal and don't need to veg long under it one is fine.

 

[rives]

Good point - I always use the Miro reflectors for the 55w lamps, so I hadn't even considered running it bare.

 

[Mate Dave]

I like the maxibright PL series. I use the powerplant sunmate also. The 110w units are the best bit of kit giving near 11000 lumens better than a 400w CMH. They are good for 18" of plant growth and then light falls off. I use then in an area W160cm x D60cm x H60cm. I hang the fixture central to the area and fill it with 10cm pots. The area the lamp isn't over is slightly dim but I compensate for that by shuffling them around when I water. You don't want the plants too close to the bulb cos they will burn but more than 4" away is wasting electricity unless you growing weak ass plants. (As my room is 60 cm tall and the lighting fixture hangs from that 60cm ceiling I just veg the plants in the 10cm pots till tey're too dam big for the little room and its time for Big School. They soon grow that tall and real dam healthy too!

The Phillips bulbs are best!

8000 lumen’s minimum for optimum growth,

 

[qupee]

Good point - I always use the Miro reflectors for the 55w lamps, so I hadn't even considered running it bare.

And in case OP doesn't know, http://ahsupply.com/

Reflectors are here http://ahsupply.com/mcart/index.cgi?code=3&cat=9

At least those are the ones I'm most familiar with.

The thing about 1x55w is I just don't feel like the light spreads out very far to the sides so it doesn't provide that good of coverage on the edges. And if a space is too small to fit 2x55 or it's just for clones and/or very early veg, you can use less power/cheaper setup than a 55w pl-l.

 

[iamoni]

I'm hoping to veg on scrog.tucking new growth under the screen.

 

[TheCleanGame]

Love the PL-L lamps... wish I still had a few.

Stick with watts per square foot instead of lumens and you'll be right as rain. Approximately 55watts per square foot, up to 65watts per square foot is pretty decent for flowering. I always try to veg under bloom wattage for at least a week before flower... Moving plants closer to the lamps for that week can accomplish this nicely.

PL-L lamps put out the most heat at the base, try to position the base as close to your exhaust as possible... preferably with the airflow of the box coming across the lamps then the bases and then out. Not absolutely necessary, just helps with temps.

The light density drops near the base end... light starts a couple inches from the base so you're looking at about 20" or less of the lamp that's projecting light. (Always wanted to put the bases in a cool air channel with just the lighted part of the lamps in the 'grow' area. needed a sheetmetal solution though due to heat)

You can offset the low light at the base by flip flopping your bases... it won't be 'full' light at the ends but it will be more than if you had all bases on one side.

Keep it Clean!

 

[iamoni]

will do!
Thanks everyone guys! You give me a lot of nice tips. Specially TheCleanGame about pointing out that the heat is highest as the base. This will help me plan my design because I have temperature issues here.