Upgrading lighting

[Robw]

The tank measures 36" x 20" H x 18" with a 4" sand bed. It has a center brace that is non transparent so I really don't want to go with a single 400 watt. As I mentioned I am adding a chiller so there will be no over heating issues. I will be building a new hood for this upgrade. Love that DIY stuff I am planning on 2 SA 10K 250 watt and two URI VHO actinics. Aclimatization could be a problem though. I have read about using window screen. How many layers would you start with?