[Frogger]

If you go with the premium light which is the Radion XR30 G4 you would need a minimum of 2 units. To decrease coverage and reduce dead spots you might want to go with 3 regular Radions and dial them back. You could also add supplementary T5's to provide more coverage if you go with 2 Radions.

Ideally shallow water Acros prefer a par between 250nm and 350 to 400nm. Corals can be acclimatized for higher if done slowly over time. So ideally you want to keep most of your tank where you want shallow water Acros in these ranges.

This is why a par metre is a good tool to have because your eyes cannot tell the difference between 200 par and 500 par when using LED's especially if you prefer the bluer spectrum.

On my 4' 75 gallon tank I went with the 4' ATI hybrid with four t5 bulbs and 3 led arrays. I can hit over 600nm par if I fire it up on all cylinders. The big advantage I find is I get all tank coverage with the t5's. The width of your tank is wider you could use the 8 bulb fixture.

I have a maxspect 160 watt LED fixture over my 35 gallon and the par is good in the centre directly under the LED's but fall way off steeply to below 100nm when I move towards the sides. Under 100 is ok for some LPS, softies, zoas and acans but even deep water acros want more.