Advice on CFL lights and ventillation please

[mygarden]

I have just invested in a grow tent with a floor area of around 3.5sq yds. I already have 2 x 250W CFL red spectrum lights. Is this enough for that area? I have read that plants also need some blue light when flowering, so could I use 1 x 200W CFL blue (which I already have) to boost the light levels, or would that be too much blue? I am confused about these lights. When they say 250W, do they mean their light output is equivalent to 250W, or do they use that much power? After buying the tent I am broke, so I'm hoping I don't need to buy more lights.

Also I need a carbon scrubber, and have been looking at previous DIY threads. I'm not technically minded but think I can manage to build one, once I have translated all your American names for the materials (what you call dish cloth we call weld mesh, a dish cloth is what we wash up with!)lol. But what size fan would you recommend? Am I right in thinking I can use a bathroom extractor fan, and that it should be positioned near the top of the tent? And will this extraction provide enough air flow round the plants? If not, would a cheap 7" clip on fan do the job? Does anyone know of any DIY instuctions using UK materials?

Sorry for so many questions, but this is my first grow and I want to get it right. I need to get this set up asap, as my poor plants have outgrown thier alloted space.

mygarden Reviewed by mygarden on 09-04-2008. Advice on CFL lights and ventillation please I have just invested in a grow tent with a floor area of around 3.5sq yds. I already have 2 x 250W CFL red spectrum lights. Is this enough for that area? I have read that plants also need some blue light when flowering, so could I use 1 x 200W CFL blue (which I already have) to boost the light levels, or would that be too much blue? I am confused about these lights. When they say 250W, do they mean their light output is equivalent to 250W, or do they use that much power? After buying the tent I Rating: 5

[TheMetal1]

CFL's usually have their actual AND equivalent wattage listed on the package or ballast. If all it says is 250w, then it is probably actual watts. If you still aren't sure... try to find the manufacturer website. They usually will have a bunch of info on particular bulbs. I have no experience with high wattage CFL's but I'm guessing they are somewhat similar to their smaller 26w cousins. Since you have a decent size tent, the CFL's will have to be harnessed to maximize lumen output to the plant canopy. Basically, you will probably have to keep moving them up and down to keep them as close as possible. The best way to avoid that hassle is to LST the plant. That way as the plant grows up INTO the lights, you can tie the branches down to where they are in perfect position. Just throwing a few CFL's at the top of the tent a few feet up is just going to encourage stretching. Also, figure out your "Lumens per square foot" if you are concerned about your total light power.
Total lumens divided by Square feet = Lumens p/ sq. ft.
Anything really above 4,000 is considered adequate for normal growth. Of course this is only relevant IF you keep the lights just close enough that they provide USABLE lumens to the plant, but without burning the it either.

Some recommend including red/blue spectrum in ALL stages of growth. I would say that, as long as you have a majority of the red spectrum, you should be graaavy :hippy: People do fully flower in the blue spectrum, but results have been shady. Keep in mind that, as long as heat is not a problem.... MORE LIGHTS = MORE BUDS! So adding any additional lights is going to benefit the plants.

The DIY Carbon scrubber is really simple to make and can be assembled for fairly cheap compared to pre-fab models sold online (saw one the same size as mine for over $300... mine was about $40 maybe?) The only concern with a scrubber is you REALLY can't slack off on the fan. Those in-line duct booster fans are great for ventilating small areas... but with a scrubber attached it's about as powerful as a cold fart. You may want to research ALL the different odor control remedies if you don't have the funds for a decent fan. And no, a clip fan is most likely not going to work well. You have to remember that you not only want to have air flow... you want air EXCHANGE. No sense in re-circulating stale air, so having an intake source for fresh air and a dedicated exhaust to pull air THROUGH the grow space, is CRUCIAL. Otherwise, you run the risk of mold or bud rot. It would suck to spend your last few bucks on all this equipment and have your crop get sick and die.

Hope that helps a bit :jointsmile:

[mygarden]

Hi TheMetal1,

Thanks for all that info, very helpful. But now I have more questions...

What's TFL and how do I do it?

Would I be better off getting a number of ordinary household CFL bulbs and hanging those amongst the plants with the 2 x 250W above the canopy? Would household bulbs give light in a spectrum the plants can use?

I know I sound like a complete numbskull (I'm female!), but how do I go about getting fresh air to circulate in the tent? If I can find one cheap enough online, wouldn't a purpose made extraction fan do the job by sucking fresh air in from the bottom vents? I just got back from the shops where I priced up the materials to make a scrubber, and it won't be cheap. Every thing here probably costs twice what it would in the states. And if your saying that an ordinary in line bathroom fan won't do the job, what's the point?

[McToker]

Here's another good DIY carbon filter idea. In a pinch, you could probably build it using a cardboard box instead of plywood.

http://boards.cannabis.com/indoor-gr...round-2-a.html

Most bathroom exhaust fans range from about 50 to 90 CFM. I started out with a 90 CFM fan on my tent (smaller than yours) and it didn't have enough power to pull air through the filter. I then went with a 500 CFM inline duct fan. Again, trying to save money. It will pull through the filter but still doesn't do as well as I would like. I seriously doubt it actually pulls 500 CFM. My next upgrade will be to go ahead and shell out the coin for a proper fan.

I tried the clip-on fan and wasn't happy with it. I bought a desk top size oscillating fan. That worked out much better.

Regardless of what watt CFL's you use, they need to be as close to your plants as you can get them without causing too much heat on the plant or burning the leaves. I'm using houshold CFL's and keep them about 1/2 to 1 inch from the tops of the plants. When your plants are young, keep the lights about 2 inches above the plants. Your 250's may run too hot to put that close.

For good info on ventilation, see this stickie:

http://boards.cannabis.com/indoor-gr...-progress.html

Not sure what you mean by TFL. If you meant LST, you can use the search function and find lots of instructions on the forum.

Not sure what spectrum your 250's are. I used 6700K bulbs for vegging and I have 2700K bulbs in for flower along with 2 4100K 4 foot flouros for side lights.

[michaelpeg]

unless the cfls are around 8 inches long then they are probably the equivalent of 250watts and also a 250 watt cfl will probably sell for around $90 canadian if i remember