edith

Hi there! Im new to the world of cultivation and ive read this forum quite a bit, but i remain confused as to the issues surrounding what seems to be a crucial question...HID vs Flo.

A tired question you may think, but my recent discovery of (cheap and bright) compact flo's has left me more than a little confused. The general consensus of opinion seems to be that HID lights are far superior to compact flo's, and that the latter should not be used for flowering because they dont produce 'nearly enough light'. But check the math....

A 20w CFL (from UK hardware store) produces 2000 lmns of light...so thats 100lmns per watt.

A 400w HPS (from net) produces 45k lmns of light....so thats 112.5 lmns per watt.

Brighter, but not by much. Why then, are HID lights considered to be so much better than compact's for flowering, bearing in mind compacts come in different spectrums? Surely the financially restricted grower (thats me) would not be much worse off using compacts form start to finish?

Correct me if im wrong..........

dcca

A 20w CFL (from UK hardware store) produces 2000 lmns of light...so thats 100lmns per watt.A 400w HPS (from net) produces 45k lmns of light....so thats 112.5 lmns per watt.
Dude ...thats 45k=45,000 lumes compaired to 2000 lumes right? How do you figure it is not like 22 and 1/2 times brighter?
45,000 lumes divide that by 2000 lumes and you get what?? 22.5. Get it?
Your plants are looking for the light output. They can care less of the watts.(sort of). But, they do need lots of lumes. What you need to do is figure out the lumes PSF..Then you will know how many watts you really need to have a good grow.. So what i'm saying is that you would need 22 and 1/2 of the 20 watt flours to even come close to 1 400 watt HID. If I were you I would read up some more about lighting..Happy Growing!

dcca

Distance from Source to Meter: d (feet)

Light Source Output: Lo (Lumens)

Light Meter measures Illuminance: I (foot-candles)
Area of Sphere: A = 4 p d2




Illuminance is the measurement of how bright a point source of light appears to the eye. It is measured in foot-candles (or lux). The foot-candle is defined as the illuminance on a uniform surface one foot away from the light of one candle and is equal to one Lumen/ft2. Which means a light source's output of 1 Lumen flowing through a sphere with a surface area equal to 1 ft2 would produce an illuminance of 1 foot-candle on the surface of the sphere.

Example: What light source output Lo (Lumens) would be required to produce an illuminance of 1 foot-candle at a distance of 1 foot?

Illuminance: I = Lo/A

where Lo is the Light Source Output (Lumens) and A is the surface area (ft2) of a sphere centered around the light source.

At a distance of 1 foot, A = 4 p ft2,

and so when I = 1 foot-candle,

Lo = IA = 4 p Lumens (approximately 12.57 Lumens)



In other words, for a light meter to read 1 foot-candle from a uniform point source of light that is 1 foot away, a light source of about 12.57 Lumens is required.



In general terms: I = Lo/(4 p d2) assuming the light can be considered a uniform point source (no reflector).



From this, one can determine a light bulb's minimum peak illuminance (foot-candles) when one knows its specified initial output rating (Lumens) and the distance (feet) to the observer. This is illustrated in the following graph showing the illuminance curves for lights of three different initial output ratings (in Lumens).







The nationally recognized standard of 0.1 foot-candles as a maximum level of light spillage off a property is indicated by the dotted line. If codes were designed to reflect this standard (or others), the formula for determining light placement could be as follows:

For a light bulb with an output rating of Lo (Lumens) and a code limiting illuminance to less than I (foot-candles), the minimum allowable distance from property line to the bulb would be d, where:

d = sqr_root(Lo / (4 p I))

This could be put into table form for those without a calculator handy.

dcca

"What if you want to determine how much light you need in watts? The general rule of thumb for providing light for an area is a minimum of 30 watts per square foot. 50 watts per square foot is optimal. You can determine the proper lighting for your area by using this formula: 30 watts (or 50) x ?(your) square feet. Example: You have an area of 10 sq. ft. - 30w x 10 s.f. = 300watts/sq.ft minimum or 50 watts x 10 s.f. = 500 watts/sq. ft. (optimal). Also, remember that fluorescent's are weaker and emit less light than an HID. This means you will need 5 times the amount of wattage to equal the output of an HID. So, 30 watts of HID would equal 150 watts of fluorescent's. This is why it is advised to provide a minimum of 30 watts per square foot for HID lights and a minimum of 150 watts per square foot for fluorescent's.
This is all important because the light intensity will directly affect the quality and yield of your crop. If you have less than optimal lighting your yield and potency will be reduced and buds will not develop as dense. This point can not be stressed enough. You must have the right amount of light for your space to grow high quality bud"

edith

Er, obviously I wasn’t saying a 20w was about the same as a 400W!! That would just be silly. I was saying that PER WATT OF POWER, a compact flo doesn’t produce that much less lumens than a HPS light. So for a kilowatt of power paid to the electricity company, a compact flo doesn’t produce a great deal less lumens than an HPS.

In other words, rather than the one HPS light, hypothetically, I could use 22.5 compacts and still achieve the same amount of lumens. While using more watts, I could obtain the same amount of light by paying LESS MONEY for the 22.5 compacts than I would for an HPS light. Do you understand now? How then, is the HPS better than the 22.5 compacts (apart from the watts)?

dcca

Do you have room for 22 flors that need to be 2 inches away from plants max??? You need at least 5 times the wattage output using flours compaired to a HID. Soo,400 watts X 5=2000 watts...Get it? You would need 2000 watts of flours to compair to 1 400 watt HID. HID=High Intensity Discharge.

rockclimber

HPS and MH are better just because of light penetration, that is all. Remember that every leaf absorbs 15% of usable light, so 5 leaves down there is not much light left. A HPS will penetrate deep into the canopy, say a 1000 watter. As for your argument, you are right; many persons on this board have used fluro with success. Just remember that the buds will be less dense, and therefore less heavy. Look into the EVL fluro light. Two members on this board have used them with great success so far.

JoseHempSeed

hey edith,,,

1) you can successfully grow mj using floros or hid's.

2) the more light, the better budz.

3) hid's put out more light than floros.

4) the more light, the better budz.

5) see 1).



check out this chart for some real-world comparisons of real-world lighting.

and good luck, whatever route you choose

edith

Rockclimber said that it is light penetration that’s the difference. Since I plan on keeping my plants relatively small (3 feet?), my growing area small and plan to put lights on the sides of the growroom, will light penetration be a problem? By the way, in my first post i was speaking about lumens per watt. In my second post i was speaking hypothetically about using compacts as a replacement for a 400W HID. Obviously im not going to put 22 bulbs in my grow room. As i said, im planning to keep things small so i wont need 45k lumens.

Laterz

dcca

So...how big is you grow area going to be? And how many plants you plan to grow? You can look at post above and figure out how many watts you will need once you figure out the square feet of grow space you will have. Welcome and Happy Growing!