Extra LED

What model of 585w light do you use? @UnkleSkunk is correct about the meter. For measuring light, I would favor using a cell phone app over those 3 in 1 meters. Cell phone camera sensors are mediocre at measuring light, but more accurate than the 3 in 1 light sensor. Once you have dialed in all of your other inputs (environment, nutrients, air flow), then I would spend the money on upgrading your light meter to a Quantum Meter or even one of the better ePar meters.

In my opinion not really. I feel like you have more than adequate light for your canopy but if you did want to add a little something something than I would suggest some ir bar LEDs to go along the sides of your tent. You have the top covered so why not hit the sides? Works great on big grows such as this. Hope this helps.

non dare troppa retta a quei misuratori spesso e volentieri danno numeri a caso.. non so quante piante hai ma se i 500w che usi sono reali direi che ne hai abbastanza attenzione perche la troppa luce non supportata da un aumento della co2 puo' causare piu problemi che benefici