LED
I have a similar sized tank. 20x20x10 I have a 24 vertex illumina 200 led fixture but a 12 would do even a radion or aqua illumination. It works great for frags you can turn it to 10 K ish to get growth then back to 20K for colours. Gives you a ton of options.
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360 gallon sps reef, 180 gal sump, bubble king supermarine 300, 4xmp40Wes, 2 x 6215 tunze waveboxes, 4 ghl mitras
360 Reef Tank