Could do a mix of both 400s and 250s, maybe run 20k bulbs in the 400s and 10-14ks in the 250w?
Several of my clients back in the day with large 200-300 gallon reefs that were taller tanks were lit with 1000w haildes. One in particular I wanna say was a 7ft × 30× 30" tank and two 1000w haildes in large sunlight supply reflectors hung 18"-24" off the water surface provided more than enough light /spread for the entire tank.
Even if I were lighting a standard 120 4ftx2ftx2ft that was going to be SPS dom, I'd much rather do 400s than 250s.
Just my .02
Several of my clients back in the day with large 200-300 gallon reefs that were taller tanks were lit with 1000w haildes. One in particular I wanna say was a 7ft × 30× 30" tank and two 1000w haildes in large sunlight supply reflectors hung 18"-24" off the water surface provided more than enough light /spread for the entire tank.
Even if I were lighting a standard 120 4ftx2ftx2ft that was going to be SPS dom, I'd much rather do 400s than 250s.
Just my .02