Lighting: quantity and type?

[Janci]

Hi guys

I have been looking to all the tank shots with Radion lights and I can say that this did not make my choice of lighting any easier.
All tanks look amazing but there is so much difference in tank dimensions and the quantity of used light.

My tank is L.1320mm x W.800mm x H.550mm
Or in more convenient dimensions
53" x 31.5" x 21"

I have now a combination of T5 (8x54W) and some led strips but want to make the switch to Radions.
Question is: how many and which light do I need?
I am doubting between:
3 x XR30w Pro
4 x XR30w Pro
6 x XR15w pro

I like to have full coverage but some how feel like the XR30's are overkill for the waterdepth that I have.

This is my SPS tank at the moment.
Please feel free to give all kinds of advice.