If you can see a difference in the light the dimmer is working there is just no way to know the PAR. I cannot believe I am going to say this but some peeps are using LUX meter Apps on their cell phones to extrapolate a PAR value. while I don't believe the numbers are accurate they can give you a power level rating. 25,000 Lux is 50% of 50,000 Lux.
The other thing you could do is measure the watts at the wall for the light.
Awesome advice. I will try the app right away. I can't see a difference in the light at all but it might be my eyes.
I just weighed a dry cup of dirt and I got 110g. I emptied the cup and got it thoroughly soaked and filled it back into the cup and slowly poured until water came out the bottom. It was 280g. Half of that is 140g and last night I was thinking they were feeling light at 150g so I guess I was on the right track. Thanks very much for breaking that down for me. I also waited until it stopped pouring out and the weight was 225g in case that number matters.