Here ya go (RC's image system is tricky)
Yeah...that's pretty DIY!!
So first, it helps to call out CFL by the actual wattage, not the "equivalent" so that we're talking apples-to-apples. Which means those are probably 23W and 32W lamps.
Single sided: this is always less efficient, so throwing more light at it isn't likely to help
Not being able to remove and scrape the screen is problematic on many levels, but like you said, you have to do what you can with what you have.
Honestly, from the limited pics I see, you're growing a decent amount of algae.
I would be concerned about the salt creep on the lamps, I can see it in one of those pics and that will cause hot/cold spots on the lamp tube and they will be prone to shattering. You need to protect those, and keep them clean
Also you need to place dome or cone reflectors around those lamps to direct the light forward. With the lamp out in the open, you're losing a ton of intensity.
Fluorescent lamps (tube or curly CFL, etc) are all different combinations of phosphors depending on the manufacturer, so 2700K is not exactly the same from brand to brand. But, my advice is to still use 2700-3500K (Warm White) when using fluorescent.
For LED, you can use a full spectrum but using a grow lamp is going to be better - something with primarily 660nm Deep Red and very little of anything else - maybe some Royal Blue, Deep Violet, but I would stay away from lamps with heavy 630nm Red.
But going back to the basics:
http://algaescrubber.zohosites.com/
http://algaescrubber.zohosites.com/planning-your-algae-scrubber.html
Starting with feeding, you're feeding on the level of about 1 cube/day, roughly. That would mean that technically, if this were a 2 sided waterfall, you would only need something like a 4x3 or 4x4 screen. Change that to one-sided and that's still only a 4x6 screen or maybe 6x6. Now...that is the "ideal" type of setup, where you have a nice even sheet of water, your screen is roughed up properly, lit directly with the right amount of light, etc...clicking on all cylinders.
Yours has a lot of fudge factors that you have to throw in there, so I wouldn't say that you're far off the mark. It's oversized, but the light is a mixture of various things, so the light levels are probably OK.
If you don't think you are getting very good growth, this could be due to other factors not related to the light.
Flow could be a factor - I can see that the pump is just discharging open and dumping on to the screen, so that's a bit unpredictable, and probably doesn't start out as a even sheet. This scrubber is probably more like a slanted scrubber with a point source for water, which is on the lower end of the efficiency curve.
Single sided reduces efficiency because the light can't penetrate as deep for as long (throughout the growth cycle) and thus you get shading, die-off, and detachment. So you have to increase the frequency of your harvests to account for that.
Detritus could be building up due to the fact that you can't remove the screen, this might not be helping either
But the bottom line is this: how does your tank look? How does your water test?
If these are OK, then don't worry about how much algae you are growing...it's doing the job.
