Best ratio of Lumens/sq. ft.?

[Legalizdahurb]

ah nice cfls so they wont give out much heat.

[StonerDave]

I dont have enough plugs for all that. it's 1 lamp HPS ballast and bulb, with a MH conversion bulb. would adding UV-b make a difference with the intense Lumens I would be using from the HID bulbs?

[amstron]

A 250 watt fixture will supply enough light to cover a 2.5 foot by 2.5 foot grow area. (6 plants or less)
A 400 watt fixture will supply enough light to cover a 4 foot by 4 foot grow area. (12 plants or less)
A 600 watt fixture will supply enough light to cover a 5 foot by 5 foot grow area. (18 plants or less)
A 1000 watt fixture will supply enough light to cover a 7 foot by 7 foot grow area. (30 plants or less

I dunno, these seem a little outdated, its generally recomended nowadays that
250= 2 by 2 ft
400= 3 by 3 ft
600= 4 by 4ft
1000= 6 by 6ft
although I grew under a 250 watt light in a 2.5 by 2.5 area and got an okay yield with strong buds

[amstron]

if you have a 1000 watt fixture, i wouldnt bother with this UVB bulb as the light output would be so little compared to the HPS that it wouldnt make much difference. Reptile bulbs are like 15 watts

[karmaxul]

amstron I would increase those numbers by 25% each for primary light coverage. You can test it with a light meter. Secondary light extends a bit past but you will need to rotate to grow with it.
325 watts of flouros = 1000 watts of HID lamps for lumen output.

One love
c

[Zandor]

I guess I will piss you all off then and rain on your parade.

My light meter and experience tells me A 400w HID light is only really good for about a 2x2 square or you loose most of your light penetration.

For example:
A 400-watt MH from 0â?� to 12â?� is about the same luminance say 55000
Same light at 24â?� the luminance is now about 30000

Still good

Same light at 36â?� the luminance is now about 1200
Fan leafs block most of the light so nothing below sees enough of the light of day to do any good.

Do the lumens math it does work.

I=L/D²

Lumens received are a measured in watts-per-square foot or foot-candles. Calculating foot-candles or lux is a more accurate way to estimate the amount of light plants receive. This still only measures how much light you plants have available but not how much your plants use.
Light diminishes exponentially fast!

The closer your plants are to the light the more lumens they receive the better they will grow, as long as the heat from the light does not burn the foliage


1000w HID lights are good for about 3x3 but you can push them to 4x4 but I would not with out overlapping lights.

For example:
A 1000-watt MH from 0â?� to 12â?� is about the same luminance say 140,000 lumens
Same light at 24â?� the luminance is now about 30000

Still workable and not bad.

Same light at 36â?� the luminance is now about 1200
Fan leafs block most of the light so nothing below sees enough of the light of day to do any good.

That is the quick answer, do the math before you place your lights. If you are using a hood then check the light pattern in a dark room before you put your plants in there so you know who will get light or not.

[karmaxul]

Thanks, excellent info Zandor. I grow short plants so I dont have to worry about penetration.

My tracked 1000 watters with parobolic shades hanging straight down grow my a 10.5 x 8.5 canopy when I rotate the crop twice a week. Once again short plants.

One love
c