What size CFL to use

I'm currently constructing a grow box and am wondering which size CFL's to use. I have made one before with 6, 26w (100w equiv.), and another with 4, 26w bulbs. Both ran pretty hot. Around the mid 90's. I was think of maybe using 3 or 4, 40w CFL's (150w equiv.). Does anyone know if this would be cooler or hotter than using the 26w bulbs? Outside temps were usually around 70-75 back when I used these.

I also have another box I build with a 90w UFO in it. Outside temps are about 60-65 and inside it is staying around 83. I was going to add CFL's to this box but I think it would get too hot.

Also can I put in a piece of plexi glass as a heat shield from the lights? It wouldn't be a perfect fit around the side but I would need that for air flow anyways. I have a fan on top sucking air out and pushing it through a carbon filter. The air intake is at the bottom of the box. Do you think this would work?

If I ever get my camera working again I'll upload some pics of the boxes so you can get a better idea of what I'm talking about.

i cant believe cfls make it that hot in ur box with air intake. i wouldnt use the plexiglass...ur already low on light the glass would just lower ur lumens... i think best solution would be better ventilation. but dont listen to me im just a noob

OK.. wattage is not the important question. What spectrum? Day CFL's are a lot hotter.. 5500-7000. "Warm" CFLs are cooler.. 2500 to 3500 or so. Also depends on size of box and venting. You can add glass tto cut down on the heat and vent both sides of the glass. Search for a guy on here called 'v12xjs'. He's got a killer PC case with glass partitioned CMH (Ceramic Metal Hallide.. GREAT for flowering, oddly) and his plants are AWESOME. BTW, CMH > CFL for certain. Also, look into T5HO 3500K spectrum. Those might be the answer to your dilemma. VERY cool, lotta lumens.

Bottom line, there are more options than just MH, HPS, CFL.

~ER~

CFL's and LED's dont get that hot. If you box is going up that much, you need to seriously increase your ventilation! As for the lights, you want at least 150w of flouros to get any sort of a decent plant. Ive grown with flouros and ive switched to HPS and i will never go back. Flouros give you a quarter of the bud sites and grow at a quarter of the speed. Save up for a fan and a 400 watt.

6" Axial fan 70 bucks
400w HPS with Ballast 160 ,200 if you want a sweet digital one or 100 for a used one

It makes its money back in the first batch

I grew cherry tomatoes inside once with one 42 watt 6500k (cool day/full/blue spectrum, best for vegetative state which runs way COOLER than 2700K lights, the guy who posted b4 me misstated the opposite). Once the tomatoes flowered I added a 27 watt and 42 watt warm (that's why it says warm white on the2700k package and cool white on the 5000k package) cfl in the 2700K spectrum. Spectrum 2700K Cfl's are more in the red spectrum, and replicate the sun more during the fall harvest, and are WAY hotter. I could have the 6500K lights touching the plants, but 2700k cfl would burn burn burn. The bluer veg. light I could wrap my hand around all day and even unscrew a bulb thats on and my hand would not burn, I tried. But the redder lower K, like 2700 K are way too hot to touch for even a second. Not trying to be a dick, its easy to mix up numbers and say the wrong thing (i just did it and had to re-edit this post), just don't want you being mislead.

I was getting those 90+ temps with 6, 26w warm CFL's. The box is 2 rubbermaid containers stacked open end to open end with weatherstripping. I have a squirrel cage blower on top with one intake connected to a hole in the top of the box. The exhaust for the fan is attached to a 4 inch vent duct leading to a home made carbon filter consisting of chicken wire, pant hose, and activated carbon. I am not sure on the CFM of the fan. I taped the other intakes of the fan shut so it pulled only from the box(this made it work harder, sounded like it was speeding up). At the bottom of the box is a 2" intake. Holding a lighter to the intake you can see there is good negative ventilation.

This is the info from the box I built 2 years ago which I no longer have. Everything is the same except the box is bigger. Depending on what other fan I get will make a difference on which of my new boxes this fan will go on.

The fan was a small grey fan from wal-mart. Looks like those paint drying fans with the intakes on both sides. Was only $14 and I haven't found another one since. I guess I could use the fan for both boxes. Attach vent ducting to both intakes of the fan and lead one to each box. I was going to use it just on the big box and have one intake sucking from the top on both sides.

Rough dimensions of my new box is 25"L 13"W 34"T. Slightly wider and longer in the center. It's 2, 30gal containers. The old box was 2, 18gal (I think) containers.

The box with the UFO, 9:1 ratio red:blue, is 2 of those big round buckets people use to keep beer on ice at cookouts. 16" diameter at the bottom of bucket 19" where they connect. 32" tall. It's staying at a good temp now, about 81-83 with the squirrel cage fan sucking air out with the other intake sucking air from the room. I wanted to add 2 CFL's to it though (cool white for veg and then warm for flower) and I think this will make it get up into the 90's. I also just closed off the heat going into the room which is why the temps got better.

I also have small 4"" blade diameter personal fan from walmart inside to keep the air circulating. Although sometimes I think this actually raises the temp of the air in the box sometimes. Haven't done any tests to find out however.

Oh and I lined the box with multiple layers of white duct tape. I had to triple layer it or more to keep light from shining through the plastic. So I'm sure it's a little insulated from that also. I tried white spray paint which worked really well but it cracks and chips after a short while and doesn't keep the light in. I have discovered if I do a layer of tape inside and outside it works much better at keeping the light inside the box.

Oh, one last thing. The old box I kept in my closet. Door open it was usually 88-95, closed sometimes over 100. These new boxes I will probably put in a closet also but the temp in it is usually very cold. I know it will not be cold though once the box or boxes are in it.

Ok, I think I said about as much about it as I can. Hope it makes sense to everyone.

Ah ok, the post above mine was posted while I was typing that ridiculously long explanation of my boxes. That makes more sense about which bulb is hotter. When I finish the 6 bulb box I'll probably do 4 cool and 2 warm for vegging and vice versa for flowering. Would you all agree on this or should I go straight cool for veg and straight warm for flower?

oh and the 42 watt 2700K outperformed the 27 watt 2700K by far. the tomatoes underneath the 27 watt bulb were scarce, smaller, and plants were smaller in stature, even though I had both lights within a few inches of the top of plant.

Well I put the 2 daylight (6500k) 26w cfl's into the box with the UFO and I'm proud to report a steady temp of 83.5 with a room temp of 62.3. I'm happy with that. At least until summer gets here. Seems right though. The boxes in the past have always been roughly 20 degrees higher than room temp. I haven't tested it with warm white cfl's though. It may jump a bit more from those. I also turned the fan up to high. I had it on low before.

Checked it again a few hours before lights out and it was holding around 78. I think this will work out fine.