My Phals get that amount of light. As measured by the fact that I can barely cast a shadow over them. But in the early morning they get very strong, yet mottled sunight. And this is enough to tinge their leaves reddish.
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"We must not look at goblin men,
We must not buy their fruits:
Who knows upon what soil they fed
Their hungry thirsty roots?"
See, I don't like this effect with Phals. I know lots of folks do, but I like the edge of darkness where leaves are nice medium green, yet plants bloom from year to year. That's just me. Now with Brassias/Oncidiums/Encyclias/Cats/etc - that's different I push those suckers till the edge of purple.