it apears UV diodes are getting cheap and very efficient https://www.ebay.com/itm/5pcs-LG-3535-UV-5W-High-Power-LED-Emitter-Ultra-Violet-380-385nm-395nm/273009904022?var=572239901923 bestva adds 420 and 470 nm LEDs to their lights but no one use UV below 400nm. a few years ago I read that TRW...