Does giving phals direct sun for one day makes a difference in its overall health?
 

This question might sound completely strange and dumb, but I was wondering if giving phals direct sunlight one day out of the week makes a difference in improving its overall health?

I keep a Phal. amabilis in my bedroom where it gets northern exposure, which means it only receives indirect sunlight bouncing off from the concrete street at ground level (my bedroom is on the 3rd fl). I've been concerned about it not receiving enough light. The care instruction from the vendor noted amabilis prefer shade, but the slight purple tinges on the roots and the under leaves of my amabilis tells me this orchid has been grown in high light environment, and it seems to thrive in such light condition, as indicated by the healthy look of the plant upon first arrival. I have a west window where I kept all my other orchids, I have been bringing my amabilis over every other weekend to get some supplemental sunlight, it responds quickly by developing small patches of purple, and then the purple tinges would slowly fade through out the week until it receives the next round of sun exposure. Am I benefiting the plants by doing so? or is it a completely waste of effort and time?:(

A bright green color of the leaves will indicate it's getting enough light. Maybe place it behind your other orchids so the sunlight reaching it is filtered slightly. Just a thought.

I would worry about burning the leaves. The purple colouring likely means it is getting the upper tolerance level of sun. Any plant needs to be moved into bright light on a gradual basis as it needs to acclimate. Just like us, if we have our skin covered all winter and go out and suntan the first hot bright day in spring, we will likely get a nasty burn. As mtorchid suggested, I would try and filter or reduce the direct light somewhat and then you could possibly leave it there all the time.

If your phal has bloomed under your conditions, it's probably getting enough light. Direct mid-day sun can burn the leaves. But phals can take direct sun during the morning or evening hours, when it's not so bright. I don't know if more light will make the plant healthier but it might make it grow faster. I always feel that a plant that produces adequate flowers is probably getting sufficient light.

Obviously, avoid burning the leaves, but 1 day a week of brighter light can definitely make a difference. Like getting 1 sunny day a week when most days are cloudy.

I grow my phals in pretty bright light outside in the summer where they get a little direct light but mostly very bright shade. Indoors, though, the light in your window cannot possibly compare to full sun outdoors. My plants react to it as if it is very bright shade. I grew all my phals, including the amabilis, in a south-facing window last year and they were fine. This year, they are under my T5 lights and getting pretty strong light. The phals are all growing new leaves and the ones that are mature enough have all spiked, including the amabilis. My amabilis does have a very light purple tinge on the top leaf but that does not seem to be causing it any grief. :)

I find amabilis very forgiving of conditions.
I have two. One is a keiki off the mother plant.
The mother plant sits in my south facing kitchen where it gets what I consider the upper levels of phal lighting.
It blooms about 20 flowers a year.
10 on two spikes.
The other is in my north facing window. It also grows and blooms every year.
The main difference is I get about 5 flowers on one spike.

If you really feel it's not getting enough light maybe move it to the west window, but further back than your other plants.

My phal is in a south window and gets mid morn to early afternoon sun and it seems happy.

I was going to start another tread. My Phals have a sun tan from too much light i think. They get a reddish purple color to the leafs. they grow really well and bloom great for me.

Less than one hour of direct sun during the midday can cook your phal to death.
If you don't believe me, test one and see what happens. lol

Presence of purple pigment is not necessarily a good thing. While it is normal for certain plants to show such pigmentation when exposed to high light, your plant is just trying to protect itself from sudden increase of light intensity.