T5 distance & time

[mexorchid]

best boyfriend ever made some of his aquarium lights free for my orchids. I have now 2x24W T5 bulbs, 1 white, 1 blue (probably not the best but well, that's what I got). On top I put aluminium paper so the light reflects better towards the plants. They are mainly cattleya seedlings and they are right in front of a north facing window in Quebec C, so it's just a light addition.

Now my questions are:
- is the distance ok? the leaves are 10-15cm under the light. 1 mounted BC even reaches up to 6cm. ???
- how many hours should the light burn?

Would be happy about your advice, thanks!

[naoki]

So is it really a blue bulb (maybe for reef aquarium)? Or is it cool white type?

I posted some measurement here:
http://www.orchidboard.com/community...tml#post572079

I don't know about the blue one, but white one is giving about 600fc or more per bulb with 15cm. Probably the distance is ok. The intensity is at a low end for most Catt hybrids (but around 6cm, it should be getting enough).

A few catt species are facultatively photoperiodic (which means night length can influence the initiation of flower, but it is not "required"). But you can use a longer day length to compensate for low intensity (compared to sun light). Most people seem to use 12-16h/day.