I disagree, respectfully. That cold temp is also going to affect other stuff, relating to metabolism, etc. There might be other issues. But honestly, I'm surprised nobody else noticed or mentioned that that temp is way to cold. If it were under hid, the plants would probably be around 75F+. But now, it's definitely under 70F. *The plant*.
@Urso hidro Get yourself an IR thermometer, if you don't already have one. You won't regret the $20 it costs (or $6.00 USD)

.
Edit: also, OP, try the PAR/LUX meter app in my signature. iOS or Android. Free at the moment. Compare the lux reading from the app to the one from your lux meter - if you want, I mean. I'm curious.