The reason most of us say that coral needs a mature tank is beacuse the tank will have gone through the PH swings and levels of CA
will be generally stable. Also a mature tank is going to have the biological filter to handle the bio load of the tank and keep the water parameters stable.
corals under PC
lighting you will not get the intense colors you see in peoples tanks. SPS
corals need that high light to maintain their color. I have PC
lighting over my Frag tank and I only keep my SPS
frags in there long enough for them to start encrusting on the plug or rock and then they are moved back into my display to color up for selling.