Various interesting links about lighting.

[isurus79]

Originally Posted by DavidCampen

I believe that T8 and T5 bulbs are comparable in efficiency. T8 may even be a bit more efficient than T5. This will also depend on operating temperature; IIRC, for T5 lamps the optimum operating temperature is a bit higher than that for T8 lamps. I use T5 fixtures because they are more compact than T8 for a given amount of light, not because of any difference in efficiency.

My purpose for using far red (>700 nm) would be to simulate long nights (by rapidly converting Phytochrome-FR to Phytochrome-R) so that short-day plants will bloom even though the lights stay long enough that they otherwise would not bloom. The increase in plant mass report is just something I stumbled across and was not my motivation for considering far red. For artificially creating long nights I would use a short period of far red at the end of the lighting period.

Most LED fixtures that use red LEDs, unless they specifically mention far red at > 700 nm, are likely using LEDs that emit at 620-660 nm

Great, thanks for the info!

So can you use the artificially long nights method only on more temperate plants then? I would imagine that this technique would be less effective on plants with traditionally equatorial habitats.