This can be tricky
How many plants are you trying to flower with that light?
Is it an auto flowering or Photo plant?
How many hours a day you running the lights?
SF 2000w is A 200 actual watt light, @16" it is supposed to be around 850PPFD @100% power, about where you want to be at the last weeks of flower running a 12/12 light schedule for photo plants
This would give you a DLI of around 37
DLI should be between 30-50 during flower higher number used during the stretch these numbers very by grower and style of growing
Look into getting a light meter app, I use the photon app so you can hold your phone up around the top of the plant and get a close enough reading to actual PPFD to convert to DLI
Here’s a good read on lighting
Have a great day 