Answers about CFL, HPS, How Much Light...

Discussion in 'Indoor Lighting' started by Roughrider, Nov 13, 2007.

  1. Roughrider

    Roughrider Registered+

    Without going into gross detail, the primary wave spectrum for blue light growth is around 435 to 465 nm, and around 660-680 for red light growth. The luminous efficiency and lumen/watt conversion rates are similar for both. So lumens are NOT are perfect indicator of light efficiency overall. They are, however, pretty good for the wavelengths used in plant growth. All sorts of other formulas can be used to compute different sorts of things related to light. They're complicated formulas. They aren't necessarily better. For most people doing small to medium grows--and I am talking about people using 400W or lower HID lights and/or LCD lights--it can be a tremendous pain to work out information that may or may not be helpful.

    I have great respect for people who can work out formulas for luminous flux and PAR watt variations and things like that. If the information is available on the box for normal growers and there's a simple formula to figure out the efficiency...hey, I'm all for it. But it's my experience that this sort of information is not readily available, is not necessarily provably (or measurably) better, and is often difficult to compute for grow areas. Lumens, although imperfect, have the following things going for them

    1) Usually listed for bulbs
    2) Proven effectiveness
    3) Easy to use formula

    On these boards, I think people look for those three factors.
  2. oSecretGardeno

    oSecretGardeno Registered+

    From what I understand, that is correct. That is what I am using right now (6500K) for vegging. I just got my 2700K CFLs for the start of flowering. As for prices, I am from the US and I got 105W 6500K for $19.95 each. It claims they put out 6720 lumens each which is great for small grows (that puts my grow at about 4900 lumens/sqft). As for the 2700K CFLs, I couldn't find them in the same high wattage, so I got four (4) 55W 2700K and two splitters to give me a good amount of lumens and coverage. Those cost me $13.95 each.

    So look around and you might find them. I order all my shit online with my girlfriends card and send it to her place, so I don't worry about that. As for finding those wattages in stores for that price ... goodluck.
  3. darkdestruction

    darkdestruction Registered

    why are my cfls giving out so much heat? i thought flouresents were almost heatless like ive read on probally 40 different sights.
  4. URfinest60oz

    URfinest60oz Registered

    is it effcient for the plant to use a 600 watt hps light from start to finish for 4 plants in a pretty spacious area?
  5. Roughrider

    Roughrider Registered+

    Unless you're planning on truly large plants, 600w isn't just's overkill. A small plant takes up 1 to 1.2 sq. ft. A medium plant takes up 1.2 to 1.4 sq. ft. In other words, 6 sq. ft.--an area of about 30" x 30"--will grow you four good sized plants. We're talking plants about 30-36" in height, the kind you get if you start flowering at around 12" to 15". A 250w will actually handle that pretty well, although most people go for a 400w.

    If you flowered longer--say 6 or 7 weeks--you might get plants that are over 4" tall. Say you gave each plant almost two feet to grow in; 22"x22" for each plant. That's around 13 sq. ft. You'd definitely want a 400w for that. But here's the deal. At that height, you start to lose light penetration, even from an HPS...even from a 600w HPS. If you've got the overall space and the ventilation, a 600w will do a great job on four really big plants. But if there's any issues with size or heat or ventilation, you might want to scale back. Like I said, even a 250w will take care of four medium sized plants.

    And that's for flower. Big lights are kind of a shock for small plants just starting out. You're better off starting under CFLs for a couple of weeks, then switching over to an HID light. I have one other thing that I consider important. When you switch to the HID light, keep the light a good 6-8 inches higher than you need to have it for the first day or two. Lower over the next couple of days after that so the plant gets used to the increased light.
    Last edited: Dec 11, 2008
  6. URfinest60oz

    URfinest60oz Registered

    OK THANX :thumbsup: i dont kno the exact measurements of the space, but am sure it will accomodate 4 big plants in height but width is pretty restricted but shud accomodate for a bushy plant, ventilation is amazing the room has got its own ventilation, thts why i choose the space! they seem to be doing fine just two plants are growin more rapid than the other two.

    also when you are giving me measurements are u tlkin in inches or ft? jus a bit confused on tht part.

    wb :smokin:
  7. ForgetClassC

    ForgetClassC Registered+

    does anyone here know if a mercury vapor light/ballast will start a MH bulb?
  8. TheGatorViking

    TheGatorViking Registered+

    Very good information brotha! I apperciate the effort and time you put into this. Its gonna change how I grow my plant. Thanks!:Rasta:
  9. TheGatorViking

    TheGatorViking Registered+

    Can I do one 600 watt HPS for 1-2 plants? Is that enough? How fast do they burn out?
  10. syde00

    syde00 Registered+

    you should probably start your own thread to ask questions... but to answer your question, 600w HPS is far far far more than enough for 1 or 2 plants.

    It really depends on the sq. footage of the space your grow is occupying though - meaning if you keep the plants smaller, you can grow alot more than if you want to grow them to be 4' or more.

    if you read the first post of this thread, then you should know that ideal is 5000+ lumens per sq. foot

    a 150w HPS light puts out ~14000 lumens, which means a grow space of 3 sq. ft (say 1.75'x1.75') that would put you at just a tad under 5000 lumens per sq. foot. (like 4600ish).

    a 250w HPS will kick out ~28000 lumens, which basically means you can double sq. footage compared to a 150w HPS

    a 400w HPS kicks out ~50000 lumens which again means you can almost double your space compared to a 250w. with a 400w you could do about 3.33x3' space.

    but going by the number of plants is just not good, as there are so many grow-style factors that will come into play with regards to how many plants you can fit into any given space.
  11. ultimatefreak48

    ultimatefreak48 Registered+

    Ok... Im looking into getting an HPS light, 150 watts possibly, but do I absolutely need a ballast... Ive been looking around to see if i can find out if i do or not and I cannot find a clear answer. Can I just plug it into a regular lighting fixture?
  12. Italiano715

    Italiano715 Registered+

    Negative ghost rider.......
  13. ultimatefreak48

    ultimatefreak48 Registered+

    Negative to being able to plug it into a regular socket or needing a ballast?
  14. Roughrider

    Roughrider Registered+

    Yeah, you need a ballast. HID lights ("HID" stands for "High Intensity Discharge"...both MH and HPS are HID lights) have to have a very regular energy current flowing into them. The current that flows through a typical outlet fluctuates too much, and that fluctuation will cause the lights to fail.

    I know people that really like to DIY everything built their own ballasts, but I think it's kind of kooky for 150w and 250w lights. You can get a full 150w light system with a bulb for about $80-90 shipped...that's not much more than cost of the parts and bulb. A 250w switchable ballast is $150.

    If you're thinking of getting a 150w HPS, keep in mind that a dual clamp light CFL setup with 180-190w will set you back less money, is more flexible (you can get daylight CFLs for vegging), has less problems with heat and therefore ventilation, and will put out nearly the same amount of lumens.
  15. Deejay2163

    Deejay2163 Registered+

    Is a 400 watt HPS enough for a 2.5 ft x 4.5 ft room? Would I be better off with a 600 watt HPS instead? Thanks in advance for your reply
  16. Roughrider

    Roughrider Registered+

    Short answer--yes. You've got a little over 11 square feet of space, and a 400w HPS puts out 50,000 or so lumens. So you're around 4500 lumens/sq. ft. that's enough.

    You may have a problem with the shape of the room, though...if your reflector is getting light out evenly (in equidistant areas, like a circle), the outer parts of your grow area won't see as much light. You'll probably want to rotate your plants frequently, or invest in a light mover. Or, if you want, go for the 600w. More energy and more heat, of course...but more light too.
  17. 1zulu1

    1zulu1 Registered

    Great thread RR.

    Ive been looking at lighting for my 1st grow and was going to go with a 250w cfl, thinking it would be cheaper to run. But after reading your 1st post it seems a 250w HPS would actually be cheaper to run plus the added benifit of more lumens. Only downside is the possible heat with the HPS
  18. koloradokid

    koloradokid Registered

    He definitely helped me more than bomb diggity.
  19. koloradokid

    koloradokid Registered

    roughrider, thank you.
  20. kwaaluudekid

    kwaaluudekid Registered+

    CMH bulbs

    I was given a bunch of track lighting that uses CMH (ceramic metal halide) bulbs. the casing for the fixture itself is a spotlight. right now I have a 2 foot x 2 foot area with 4 of these spotlights CMH bulbs on them and they're ready to go into flowering stage at 28" high. I was wondering if this is a decent setup and should I add more light? (I have probably 20 more fixtures and bulbs). Here is some info I found out about the bulb:

    GE ConstantColor CMH
    CMH20/TC/UVC/U/830/G8.5 (info from box)
    3000 kelvin color temp
    1650 lumens
    LPW efficiency:80-105
    color rendering:80-93
    color temp:3000-4200

    website with info regarding bulbs: (go to page 28 for info regarding this bulb. first one in list)

    Was also thinking of adding a light or 2 to the sides (these are spotlights after all) to get all-around light, but so far it seems to be going good with just the 4 lights on top. Am hoping to start flowering in a week or two, so my questions are:

    1. is this a good bulb for growing? veg? flower?
    2. how many lights per sq. ft? (in case grow area increases)

    right now only using bagseed, but will have some cuttings soon, so I want my getup as good as can get for the cuttings. Thanks for your help in advance

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