Stick with T8s -- the light output of 4 T8s vs. 2 T5s is virtually the same, but you'll pay a lot more for the T5s. Spend what you would have paid on the T5s on more orchids.

Julie

Julie is correct. Both T8 and T5 use electronic ballasts and have the same efficiency (lumens per watt) the T5's are brighter because they use more energy. Someday when they are not so new and niche the prices for T8 or T5 will become more equal but for now the established status quo is the T8.

H

OMG, what a day this is. Howard... said... I... was... CORRECT! Must write this down in my personal journal ASAP ;-)

Julie

^_^ ic ic

i found a garden store selling plant use T5s for $35 for one 48" 55watt light--includes the fixture, the ballast, AND the bulb
that is not expensive at all. besides i know a fishstore owner who was also willing to sell me a T5 for the same price

but yes, when it comes down to it, a set of 4 T8s only costs like $45 while the T5 costs $75 (with tax)

T5s look cool though.... i don't know yet...

Think of the long term cost of replacing those T5s. You buy the T8 fixture for about $10-$20, then replacement bulbs are about $5 each. For T5s, every replacement costs you $35. Think of all the nice plants you could be buying with that money instead...

J

P.S. My first light purchase were T5s. When they're done, I plan on getting T8s instead for that spot.

Personally I use T 12s along with CFLs and they work just fine. I can't see replacing three T12 fixtures just because T8s and T5s are new.

T12 fixtures are no longer readily available anymore. They're being phased out in favour of the more energy efficient T8s; many electronic ballast (correct me if I'm wrong) fixtures can accommodate either T12s or T8s. I have some of both and they really work pretty much the same except that the T8s use up a bit less electricity and there's not that buzzing sound.

Julie

GOOD POINT
i did not think about the replacements
this definately puts T8 over T5s

My question is this, economics asside, does T5 bulbs put out a color spectrum that is good for growth, flowering, or both?

I'm quite certain the spectrum of T5s and T8s (and T12s)is the same...you have the 'cool' and the 'warm' bulbs, and then the kind of mid spectrum ones at 5000k too..at least that's what I've seen when I was looking around at these things. I'm still using a T12 fixture which I have left over from some decade past, and with 2 40W bulbs (one warm one cool...just happen to have this combination) the best I can get is about 1500fc at 2 inches away...meaning it's perfect for my extensive phal collection when supplemented with the bit of natural sunlight I get!

The short answer is that the hydroponics stores are selling t5HO plant lights, not t8. The same t5s are used for aquariums for proper plant and coral growth. If you want to find people who are nuts about light spectrum these are the nuts. T-8s are designed for the human eye, to replace t12s. T-5s are specialty bulbs. You can get GE t5 red shift tubes for flowering or blue shift for growth. If you mix them you will have less green than if you used all people pleasing 5,000k tubes. Total lumens per watt is a useless measure if those lumens are green light that the plant can't use.