24" T5 4 bulb vs. 2 85w CFL.

[Cowboys East]

I am in the process of building my first orchidarium to help with humidity issues for my mini orchids. I am converting a 20 gallon tank that is 30" long. My questions is, should I get a 2ft 4 bulb T5 fixture or just use 2 85w CFLs? I get 96w with the T5s and 170W with the 2 CFLs full spectrum. Do more watts translate into brighter lights? I read a post about someone using a 200w CFL and low light levels as compared to the same wattage using T5s. Want to grow some higher light orchids so I was hoping some of you might have some ideas of light levels comparing the two. Thanks for any help I can get.
Neil

[Ross]

Lots of issues, here. I would opt for the t5 straight tubes if it were me. They will be cheaper to replace annually. The CFs are more convenient, but you are replacing the ballast along with the bulb. Watts and light ouput go hand in hand. The more watts - the more light. Watts are related to size of bulbs/fixture. I would recommend the 4 foot 4-tube t5 fixture if you have room. Locate the tank under the center of the fixture where light is the brightest. Just my 2 cents.

With a larger fixture, you'll be all set if you change to larger tank in future, or add a second tank.

[Becca]

I'm with Ross, I would go with the T5's. I also recommend the 4ft instead of the 2ft, the lumens per bulb is much lower with the 2ft bulbs. But also be prepared to cool the bulbs some how, like with a fan running on them or your terrarium will be running around 90 to 100 degrees!

[HereticHammer]

I have no experience with T5s. I am setting up an orchidarium right now too (a 55g tank) and think I will go with a 4ft T5 fixture with 4 54w lamps. I'm still trying to figure out whether to go all 6700Ks or mix them with 3000Ks, have you decided that yet?

Anyway, I do have a lot of experience with Power Compacts in reef aquariums and they are similar to T5s in output it looks like to me. Almost like a power compact just straightened. They are MUCH more powerful than a regular compact lamp.

Wattage is not a good measure of light output here because you are talking about standard compact light vs T5s which I believe are HO (High Output) bulbs.

I would definitely go with the T5s over regular compact lamps.

I don't know anything about the difference in lengths and their lumens but I would think you would ideally want to have the lights run the full length of the tank.

Use the 4ft and let it hang over on one side and you can always grow some less humidity sensitive orchids there as an added bonus. It may not look perfect but who cares about that if your like me. What is important is good orchid growing right?! lol

[Cowboys East]

Hey,
I went with the CFLs because the space I have to put the orchidarium is under four feet and has a door on one side. The 2ft T5s don't do much for me and I have a 4ft shelf that will get new lights down the road. I did make my own reflector to fit my exact needs. Thanks for the info.
Neil

Originally Posted by HereticHammer

I have no experience with T5s. I am setting up an orchidarium right now too (a 55g tank) and think I will go with a 4ft T5 fixture with 4 54w lamps. I'm still trying to figure out whether to go all 6700Ks or mix them with 3000Ks, have you decided that yet?

Anyway, I do have a lot of experience with Power Compacts in reef aquariums and they are similar to T5s in output it looks like to me. Almost like a power compact just straightened. They are MUCH more powerful than a regular compact lamp.

Wattage is not a good measure of light output here because you are talking about standard compact light vs T5s which I believe are HO (High Output) bulbs.

I would definitely go with the T5s over regular compact lamps.

I don't know anything about the difference in lengths and their lumens but I would think you would ideally want to have the lights run the full length of the tank.

Use the 4ft and let it hang over on one side and you can always grow some less humidity sensitive orchids there as an added bonus. It may not look perfect but who cares about that if your like me. What is important is good orchid growing right?! lol

[ChasWG]

I went with 3 x 100 watt GE CFLs per shelf in my orchid enclosure. These are the 6500K CFLs. And the top shelf has one 150 watt CFL in place of a 100 watt bulb for added intensity. And for a bit of growing red light I added 2 x 24" straight floro. lamps. So each shelf has about 320 watts of light being poured onto the plants (the top shelf has 370 watts). I am waiting for my new light meter to measure the exact footcandles the plants are recieving. Some early tests I did using the light meter in my D-SLR indicated that I was getting around 4500 to 5000 fc at the leaf level. But if this is any indication, I have a Brassavola cordata on the top shelf and it's long green leaves are now turning a very dark, almost purple, red. The leaves are not hot and they are not burning. The plant is growing new leaves (5 in all) and it has a lot of new root growth. The dark color of the leaves is a good thing for this orchid. I have recently backed down the light that this Brassa. gets. The other orchid on that same shelf is a Neostylis Lou Sneary 'Bluebird' another high light loving orchid. It's in the most intense light area and loving it as well. Again, no hot leaves and it's doing well.

My Phals are on the lower shelf moved way out of the intense light area. I'm thinking about getting some lower wattage bulbs for that shelf. This set up seems to be working well for me. The plants are growing and seem to be happy. And at around $3.25 per bulb I think I'll stick with the CFLs and not the pricey T5's.