I'm not aware of an effective method to convert Lux (or more likely Lumen) to PAR and it also depends on the the distance from the lights. I can say that based on your comment it "looks" bright - odds are you have way too much PAR. LEDs are very efficient at producing PAR - much more so than MH or T5 lighting. The vast majority of all the light produced falls within the 400~700nm. At equal PAR, LEDs will appear to the human eye as being much "less bright". This is a large part of the reason many switching to LEDs from other types of lighting have problems.
I'm brand new to planted tanks (20 year reefing veteran) so take this with a grain of salt.
The reasonable man adapts himself to the world; the unreasonable one persists in trying to adapt the world to himself. Therefore, all progress depends on the unreasonable man. - George Bernard Shaw