There is a PAR chart in here on the RayII. With three inches of sub, it looks like you only have enough PAR for about 2 BPS in there. I have no injected CO2 so let someone else who is experienced/w that either tell you what is correct or co-sign what I said
before taking any action on it. And since you supplied no picture of the tank, it is hard to guestimate the fert need/level required based on the amount of plants in there.
If the tank is not heavily planted and those plants growing well, it may at least partially explain the high nitrates simply from over dosing and then the ferts not being used. The EI system is to keep from using up all the ferts, but still doesn't need extra doses that are not being used.
The water change suggested amounts and dosing amounts are based on a full tank of plants that are growing well. Till you get a PAR on that other light, I'd cut one of the doses in both the Micro and Macro ferts. You just don't have the growth to use up all three doses of it. Later you can always re adjust.
With just the RayII you can run 9 hrs safely and just watch for any algae.
If the spray bar is facing on an angle so it's spray makes it up to the surface about
mid way down the tank so it just creates a ripple in the surface of the water, the film should go away. In this case, if this does not remove the oil slick...LOL...you can use an air pump/air stone to help circulation by placing it at the bottom on the same end as the spray bar. I would not run one completely open but rather just enough for you to see it bringing up some water on that end. You don't want to block those pumps though. I'd use a two way gang valve, open the line valve completely but then open the unused valve till it cuts the air coming out of the used one with the stone on it.
I always put that set up on my tanks to keep back preasure off my pumps.