Maura, 3K - 4K footcandle light on even a strap leaf type slipper orchid is too much and a risk of burning the plant (in my opinion.). Growing in a green house I have found that some of my phrag orchids like light up to 3K foot candles, but paph orchids (both the darker leaves and the strap leaf) grow better in light ranges of 1000 – 1500 foot candles. JMHO

cheers,
BD