Looks like an extremely large screen, how did you arrive at the size?
The feeding-based guideline says that you have 12 sq in of screen, lit on both sides, for every cube of food you feed per day. My recommendation past that is to increase that as much as double if you are running a larger tank. But going more than double what you feed can start to spread the growth out too much - restricting the space tends to force the algae to grow thicker and greener.
The flow should be about 35 GPH per inch of screen width, which might explain why you had to up the flow so much with such a wide screen. If you are able to scale the size down per the above guideline, that would increase the flow per inch (which is always better)
CFL Lighting should be in the range of 1W per square inch of screen, either total or per side. So if you had a 12x12 screen (144 sq in, LxW calculation) then you would want between 72 and 144 watts per side - which is a lot of light, but then again, that's only if you are feeding 12 cubes/day, which is what a 12x12 screen has for "capacity"
The other way to look at it is that your screen, large as it is, will be limited in it's "capacity" by the amount of light you throw at it. So with 5x 23w you have about 115W of light, which means you probably have a scrubber capacity in the 5 cube/day range, no matter how big the screen is.
So you could leave it like it is and see what happens, if it works for you, then great! If you want to use a smaller pump (less heat/energy injected into the system) or want to up the per-inch flow rate, make the screen narrower and use the same lights, or larger wattage lamps with larger reflectors.
There's more than one way to skin the cat here. Let me know if that helps and if you have any questions...