yep, yep, yep!
that's one of the things about light measurement, there are so many ways to do it, it gets really confusing after a while. even though everyone is measuring the exact same thing! especially when you get photogs into it...
but yes, i use a sekonic digi-lite l-328 meter. it's a higher-end meter that is pretty accurate for ambient light measurement. it has seperate heads for measuring illuminance (they call it a 'lumidisc') and incident light (the 'lumisphere'), guaranteed to be +/- 0.1 EV accurate. it takes a lot of the guesswork out of the conversions, and is simple to operate.
be careful with the grey card measurements -
- what you're getting there is the
correct exposure, based on 18% reflectance, not the actual light measurement!
i'm still jealous over the kW agrosun...you're going to get some great buds...
you'll have to post some pics of the set up...