What's the difference between T5, T8 and T12?

Now, I am thinking about setting shelves up in garage, and start to look into the light fixture.

Which one is better and economical to use for orchids? I have seen/read other's setup, but still not sure what's the difference between T5, T8 and T12? Will 4 foot 4 lamp T5 fixture good enough for orchid shelves?

I can't get T5 bulbs in the four foot length at my local big box store, so for me T8 flourescent shop lights are the most economical. T5 means the bulb is 5/8 ths of an inch across. These bulbs are very flexible for a glass tube. T8 is a bulb 8/8 ths of an inch across or a one inch thick bulb. Both T5 and T8 use electronic ballasts. T12 flourescent bulbs ate 12/8ths of an inch thick or 11/2 inches, and use the old style ballast instead of electric. They are the cheapest to buy but the more expensive to run. Check the box stores in your area to see if they carry T5 or T8. I've been using the fixtures with two bulbs per fixture. If you want to increase the light, you may want to go with a four bulb fixture.

I ended up going with a 4 bulb, 4 foot, High Output T5 system that I got on sale from the Hydroponic store. I did this partly because of the higher lumen per watt rating but also I needed something fairly compact. I would have needed many more T8 bulbs to get the same amount of light.

T5 is still kind of expensive, I would guess T8 would be the better way to go if space is not an issue.

I have seen 4 foot T5's at a big box store, but they are not High Output.

Doug, You can also get high output T8 fixtures- off the internet. I've been looking at LED fixtures, too, but they are REALLY expensive! There is a 4 foot LED bulb that you use in a re-wired (without the ballast) shop fixture. I like the look of that one but don't really want to spend a couple of hundred dollars on bulbs.

I fairly recently switched from T12 to high output (HO) T5 fixtures-4 foot fixtures with 4 bulbs each. The T5 fixtures and bulbs are more expensive in the initial cost, but the difference in light output is huge. If you want to grow higher light orchids like Catts, the T5 is the way to go. Phals and other lower light orchids do well with the T12. I have never used T8.

Susan

Since I started growing a few monts back my electricity bill went up 20 / 30 a month

i got 2 2 T12 bulbs fixtures in 2 separate spots - so it is 40 w x 4.
then I run 4 24 W CFL and one 22" T5 undercabinet that is 14 W i believe.

I saw T5 fixtures oncl tubes at the home store for about 30 bucks or so -
it may be half of the wattage of the T12 but it looks brighter - even in photograph...
probably spending 80 bucks more than a T12 for a T5 is worth in the log run as it may pays itself off...

Orchidlady and Dougroc how much were your setups?

I called a local store where I normally get my orchid mix and fertilizer stuff. The owner says he has T5 4 ft T5 fixture, and if I buy 4 or 5 sets, he would even give me a discount. So I will check it out his setup next Tuesday.
DH is not pleased with the idea of using garage though...

Oh-oh Liz, Are you invading his space? Tell him having the lights on for your plants i the evening will be providing security for your garage area and make it easier to find things in the gargage.

Originally Posted by stefpix

Since I started growing a few monts back my electricity bill went up 20 / 30 a month

i got 2 2 T12 bulbs fixtures in 2 separate spots - so it is 40 w x 4.
then I run 4 24 W CFL and one 22" T5 undercabinet that is 14 W i believe.

I saw T5 fixtures oncl tubes at the home store for about 30 bucks or so -
it may be half of the wattage of the T12 but it looks brighter - even in photograph...
probably spending 80 bucks more than a T12 for a T5 is worth in the log run as it may pays itself off...

Orchidlady and Dougroc how much were your setups?

I seem to recall it being around $160 with the Philips Alto bulbs, but last time I was there it was a bit more. The local hydroponic store usually gives you a discount if you show up for cash, so I may have saved some money there.

I did see a noticeable improvement in the health of my plants after switching to my T5 system, but I still think if you do the math T8 is a better deal. (Again I was somewhat constrained on space) For a larger scale I have heard that MH or HPS is even more efficient, but at much higher cost.

The cost of my fixtures with bulbs was about the same as dougroc's. I noticed a huge improvement in plant growth and blooming over the past year.

Susan