That is what my main question is really. There is so much contradictory information out there. I have read that Catts require 4000 fc as a maximum at noon on a sunny day, but not what the minimum should be over the whole day, and then there are others that suggest they should have that level of light all day.

Am much confused!

I am happy to listen to my plants, but I guess with the catts I won't know until it's time for them to reflower whether or not they have had enough light.

I have been asking questions on a UK site too, as I thought there would be more people with my sort of conditions, but so far I have not had much joy. Hence my experiment.

Just after one sunny day, it looks like none of my windows (except my front rooms) are bright enough to sustain even low light orchids. But the readings for the front rooms went above 3400 fcs (the max for the light meter being able to read is about 33500 lux - after which you just get an error message).

We shall see....