MH bulb spacing

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Haven't received my new tank yet but might as well sort out the lighting ahead of time.

Tank ordered is 69.5l, 20w, 24d, since room divider overflows on each side. Plan is to have a full hood.

Been looking at 60", 3 bulb 175w MH/PC retro kits but wondering if 2 bulb 250W kit might be as good.

Don't have any corals (no tank) so realize general question but looking to wards soft and SPS but don't want to rule out a clam in the future.