Can someone clearly explain to me how to calculate how much LED lighting you need for the amount of gallons you have? Thanks.

LED lighting per gallon isn't realistic. This equation will give you good results. Use one 3 Watt LED per 9 square inches of surface (3"x3"). If your tank is deeper than say 12-14 inches and more intensity is needed at greater depth, use lenses/optics (80, 60, 40 degree.) If you do use lenses/optics, use a 2.5"x2.5" plan to avoid 'spot lighting'. My 2 cents.

Thanks Dave! That makes a touch more sense I guess.