Can you take a light meter to where it came from, or ask someone there to take a reading of the lights where it came from?
A free lux meter app for your smartphone would be sufficient and you can take some measurements right away. (A handheld like the "lx-1010b" I use is less than $15, delivered....I'd also suggest one of these for longer term usage. Better readings and safer over your tank!)
Post your results if you get the reading from the other tank....it might be helpful if you could also take a reading of the spot where he is now, as well as finding out what the peak lighting level is over the tank.
(All measurements will be at the water surface.)