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

[Roughrider]

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.

[oSecretGardeno]

So let me get this straight - using CFLs only, while vegging with my CFLs I should use a 6500K spectrum? And for flowering, I should switch to 2700K CFLs?
How powerful can I get CFLs at these spectrums without breaking the bank?

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.

[darkdestruction]

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

[URfinest60oz]

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?

[Roughrider]

Unless you're planning on truly large plants, 600w isn't just enough...it'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.

[URfinest60oz]

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:

[ForgetClassC]

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

[TheGatorViking]

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

[TheGatorViking]

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

[syde00]

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

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.