Alage scubber questions

Hi I'm John I have a 400g reef tank and I was looking into adding an alage scubber to it and I have some questions
What size screen should I get? I don't have much room and I haven't found a strait answer I've seen people say 12sq inch per cube of food I feed about 7 cubes daily but that comes out too only 80sq inches which doesn't seem right
Would 2 250w halogen work lights work? from what I've read I'd need 400w of cfls which I do not have the room or money for 2 250w work lights would make it much more easy for me plus it sounds like the kelvin of them is the right color for alage growth 2500k-4000k
And that's it thank you

If you dont have space or money to do things right , the only way is to thing about an ATS like supplemental filtration.
I believe You will be growing brown or black stuff when under powered or undersized, but still it is nutrient export . Not strong though

Halogen get hot enough to cook under. A picture of your space would be very helpful. Also a scrubber will replace some of your other equipment so room will actually be made.
A simple scrubber of two shop lights(metal cone ones), two 23 watt CFLs, and a single pump which more than likely you have laying around will do the job. Don't need to buy (forgive me Floyd and other DIY sellers) a fancy very well made and researched(you guys like that?)scrubber.
I never had any other equipment on my system than a skimmer which the scrubber replaced. So in my mind all those reactors and other high dollar items aren't needed. I dose two part manually.

7 cubes = 84 square inches waterfall or upflow

= at least 84 total real CFL watt bulbs 16 hours a day, replaced every 3 months

= at least 168 total real CFL watt bulbs 8 hours a day, replaced every 8 months

= at least 42 total LED watts 8-16 hours a day, never replaced, mostly 660nm (red) with some 450nm (blue).

Ok I'm glad that would work I've read you need between .5-1 watts per gallon which on a 400g tank would be almost Imposablse with cfls even 200w wouldn't be very practical