Stupid question, lol.
Well, you won't need em. BUT, you will see a big difference if you supplement additional Fiji Purple or True Actinics!!!
Not just from a appearance, as well from the Color the Coral develops.
A have a few Deepwater SPS they are like Chameleons, and take the color of the T5 there are under.
On the long run, the MH are great for growth, but T5 supplements highly recommended for the final kick.
All the good SPS farmer are using mix of mostly T5 and MH for additional PAR.
I have upgraded to 4 x 250MH pendants and wait now for actinics and ballasts on a 72" tank.
-PSXerholic