What ppfd values and height should I hang my leds at?

[CannabisMingus]

It's what I use too FWIW

 

[WildBill]

I second the PhotoBio, it's an accurate meter. Eliminates the guess work, and is very affordable.

Yup! I compared mine to factory and Dr Coco's PAR tests and my were very close.
For most here, it's accurate enough, but it still comes down to what your girls want at that particular time.