I have two t5 lights set 12" above my plants, if for some reason they start to yellow I either raise the light to around 18" or just use a window screen to add a little shade.

a window screen, thats a good idea.

i have bookmarked rays calculator, and will use it once its set up.

but, do you hold the white paper where the bottom of the pot is? or where does the paper go?

My setup
 

Hello here are some pictures of my light setup

Picasa Web Albums - corpodeanusilviu - Indoor garden

I use 2 18watt fluorescent light, 1 is cold and 1 is warm.I keep them at 20 cm from the flower stalks of the flowering plants.In the pictures you will see it all.

Please tell me what you think about these setup .

Thank very much.

it looks pretty good. i dont know exactly what lights you have, but it might not be enough for and thing that likes more light than a phal (such as dens catts oncs. etc) i see you have an onc aliance in with your phals, the onc needs more light than a phal.

yes I know that onc need more light that for y keep it closer to the lights.

The tubes are 18 watt , 1 has warm light yellowish, and the other white light(cold light), I have them from about 3 weeks and the plants seem to like them .

I read that the phals need somever 2000-3000 lumens and the onc over 3000 somewere in the 4000 lumens .

I think my light are somewere in the 2000-3000 area of the lumens . Do you think the plants are ok from the pictures I posted?

Thank you

i think that you may be talking about foot candles instead of lumens. a phalaenopsis needs 1,000-2,000 foot candles. there is a way to convert lumes to foot candles, but i dont know how. also, are you sure what you are measuring i lumens? or is it that you were measuring in foot candles the whole time and just thought that you were measuring in lumens. this is something you will have to find out. oncidium like 3,000-4,000 FOOT CANDLES

i have four 34 watt flourescent lights above my phals. and it is ten inches away. your 'chids may be fine as they are, just watch the leaves. they WILL talk to you :)

Good luck

Lumens, Footcandles, and the laws of physics
 

There seems to be some confusion and misunderstanding about light. Here is how I remember it from many years ago. If it is not correct, I apologize for my memory and hope someone quickly corrects it. Otherwise I hope it will clear things a bit.

Lumens are a measure of the amount of light that is emitted by a source.

Footcandles are a measure of the amount of light hitting a target.

Unless there are odd things going on (mirrors, lenses, reflections, etc) the amount of light falls off by the square of the distance from the source.

When you measure how much light your orchids are getting, you need to measure the footcandles at the target (the orchid). Knowing your lamp puts out a certain number of lumens does not help much. If you have two orchids, one 1 foot away from the light and one two feet away from the light, the further orchid will receive 1/4 the footcandles the closer one gets. Multiple lights and reflectors complicate it a bit.

When you're dealing with the sun outdoors, moving a plant a few feet closer or further makes no difference (unless you're measuring individual photons) because 93 million miles vs 93 million miles plus 10 feet are essentially the same.

When you talk about a window, the real source is the sun, but the apparent source is the window. If you are "pretty close" to the window, it acts like outdoors and light doesn't fall off too much with distance. The smaller the window, the dirtier the glass, and the further from it you get the more the window acts like the source of light, and the more light falls off with the distance from the window.

Sry for my mistake, the term is foot candle yes, you got the idea:), thank you for your info. About the leaves they are shiny, green and the texture is hard to the touch .

thank you

okay, thanks Bob!! that helped alot!!

refu-i figured you meant foot candles, but i wasnt sure. do you have a light meter? if not, how do you know how many fc your plants are getting?

the light has to do with the color of the leaves. some take on a purple right before its too much.

some lighting info here - a little dated, but still relevent:

AOS | HID Lighting