Question
QUESTION: Can sun tunnels (like sky lights) provide enough light for my Phals to bloom (eastern exposure with brightest light in afternoon)?

I have a digital luxmeter (light meter that measures in lux instead of foot candles) - what should the reading be for Phals?

Thank you!

ANSWER: Phals do best at 1000-1500 foot candles.  One foot candle equals roughly 10 Lux.  So you should have 10,000 - 15000 Lux. If you have a multiplier on you meter, setting it at   X1000, you should have a reading of 10-15.

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QUESTION: My light meter has three settings:

x1 for 0-1999
x10 for 2000-19990
x100 for 20000-50000

The directions for use say that if the display has a 0 or two 00 as the first number/s then to move the selector down one level. Holding the meter in the same place: So if at x100 it reads 006, I move the selector down to x10 where it reads 040, and moving down to x1, the meter reads 304. Does this mean the lux reading at 304 is the most accurate and it would equal 30 foot candles?

Thanks again.
ANSWER: You have the right idea. My expectations, however, is that I would have seen something closer to 060 when you went to the x10 reading and closer to the 600 at the x 1 setting. It is possible that you moved the mwter slightly in changing the settings.  You also should be measuring incident light.  You need to use a clean sheet of white paper and position in at the level, and in the location, where you have your phals. Point the light meter at the paper so you don't cast a shadow on that portion of the paaper you are measuring. Remember that the light intensity in the sun tunnel will vary considerably with time of year (ie sun angle) and cloudy vs sunny days. Experiment.  As you move the paper and measurement closer to the light source, see how the light intensity varies.  The 1000- 1500 foot candles is for optimum growing.  Phals can do fine at light level as low as 600 foot candles.  Clearly 30-60 foot candles are far too low.  If you live where you have a fair amount of cloudiness you might consider a four foot shop light with cool white florescent bulbs hung close to the leaves.  This provides a consistent level of lighting either to supplent light from the light tunnel or by itself.

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QUESTION: I am still struggling with this. I agree with your expectations that the numbers, at the various settings, should have been closer.

It is a clear, sunny day here. I placed a piece of plain white paper on the table, positioned the meter and tested again, placing both the detector and the meter on the table, in hopes of keeping the exposure the same.

The results were:
    at x1 = 1240
    at x10 = 142
    at x100 = 015

This seems just a bit closer, but still not quite what one would expect.

I then used the "hand and shadow" method as described in Ortho's  All About Orchids book. Placing my hand 12 inches above the white paper in the direct light, there is a diffuse shadow, which would indicate enough light for a phal.

So, I am still confused about the readings.  The x1 reading of 1240 reading would mean 124 footcandles, but the hand-shadow measurement would indicate a much higher number.

How do I reconcile this?
ANSWER: Yes, there is something we are missing here about your meter.  If you still have the literature that came with your meter and/or a contact phone or E-mail ddress for the manufacturer, it would be well to contact them with your question.  There may be some specific feature of your meter that we are missing.  It seems that the  x1 reading is more likely to be the correct reading in FC but I don't know why this would be the case. Sorry I can't be of more help.  Let me know what you find out.

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QUESTION: Thank you for your response.

The manufacturer is Mastech, the model is MS6610. There is no documentation about Mastech, just a very, VERY BASIC manual, no address, no contact name or number, not a single thing on the box, the meter or the less-than-helpful manual, except "Made in China".

I did a search on the Internet for Mastech and came up with nothing helpful.

I guess the best thing to do is to just keep track of what measurements I do get, keep an eye on my orchids to see how they do; oh, and keep my fingers crossed.

Thank you.

Answer
Thanks for the additional informtion. I have googled Msstec and found a picture of your instrument. The company is located in Hong Kong.  I have E-mailed them for information and hope they are responsive.  You can either contact me in a few days or send me your E-mail address and I can contact you if and when they respond.  My E-mail address is [email protected].