the 400 watt discharge bulb fixtures with the 400w BLB coated bulbs emit little to no visible light, basically any yardlight fixture will fire them, LL-400BLB is a common cross referancable part number, street price 30-40 each
for LED fixtures, cheap way, set them on full blue and stack a rosco R383 Congo Blue combined with R375 Cerulean Blue, that blocks most visible light, yo umay or may not have those common blues on hand
to do it proper use the rosco permacolor 3660 UV pass filter
also the LED must be emitting true UV to work, the filter will not add it