Okay, so here's the Panda Grow specs on a 200w (100w x2) CXB3590 fixture (If they had an inline x4 I'd use that but since they don't we can figure it out from this). It will be the exact same as yours but with a larger footprint...
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We'll start with this. These diagrams give us all the information we need to figure out you're setup. I will get the links for the calculations and post them up for you tomorrow. It's late tonight and I was never really able to recover from today. I helped push my cousins big ol heavy Camaro around and that is not good on my replaced hips and nerve damage. A lot of pain is breaking my concentration. I can write and post up pics like this but I need focus to make sure the math us right. When we're done you will know how to calculate PAR(PDI) and you won't be guessing about how to set your lights up, you will know they are right.
By the way, your fixture's are worth $800-$2000 (Larger 480w drivers are much more expensive than the smaller ones. If your fixture's use them instead of 2x 240w each the price goes up a lot. It's why the huge variance in my estimate of their value.) You got a killer deal. I'm envious, hehe.
*note* Ignore their recommendations for clearance. We will adjust your output to compensate for lower clearances. Closer to the plants means better light penetration and all the benefits it gives.