I have been trying to find this kind of info. for over a year now and even the manufacturer can't seem to come up with this info so for my own personal satisfaction I'm going to buy a meter for this purpose. This is the cheapest I could find with the correct type of measurement and not a bad investment(If it works correctly)if you want to keep your lighting at it's maximum output.

http://www.transcat.com/Catalog/productdetail.aspx?itemnum=401025

I have a TEK T5HO 4 lamp. Also have a meter to measure light but can only give you foot candles. With 2 lamps on and about 12 inches away from bulbs it's 700fc. Turn on additional two lights (total 4) and the output doubles to 1400fc. So I assume you get about 700fc for every two bulbs you add. Hope this helps.

It looks like you are going to get 5,000 lumens per bulb which translates into 5,000 lux if placed a foot away. Eight bulbs would give you 40,000 lux at that distance, if you move it two feet away you would have ~20,000 lux.

Mike

According to this site(below) 700fc converts to 7534.7 lux so you would be getting 3767 lux per bulb at 12". Eight bulbs would give you 30,138 lux at 12".

Here is a link that might be useful: Foot-Candles to Lux

16 inches will give you 22,604 lux or lumens going by 2800fc at 12". T5 HO specs are saying 5000 lux initially. I don't know if that means 12" or 2"