Minimum amount of LED's

[Roblox84]

I have a 125g 6 foot with two braces. What is the minimum amount of led's NECESSARY for my size tank? I keep reading posts where people put in 96 to sometimes 200 leds in tanks smaller than this, but in my opinion most tanks like that are overlighted. I see led strips selling with approx. 12 leds in them and I figured it would be much cheaper to maybe just retrofit a 48 led kit into small strips of leds. I was looking at the current usa pro strips and a 36 inch strip costs 177 dollars so obviously they are meant to just be ran by themselves with only 3 or 4 strips on a tank my size. So from this I figured i'll only have soft coral on 3 rock towers in my tank so I really just want to highlight those fixtures without spreading the light into parts of the tank that have no rock sitting on the sand bed. Each rock tower is approx. one foot or less wide so in total I may have only about 3 foot of tank in total i need to light. Thanks in advance for any help.