do it slowly ...
right now if ur pumps are still working fine , let it be .. change what is important to you .
IMO , T5 6 tubes will be great if u decided that you will not go into SPS. not changig your chiller to one with a biger horsepower is just temporary as i think u know that ur chiller RA240 is too small for ur tank size.
although changing ur light and pump might reduce the heat load , but the chiller might not be able to take the vol.
a very simple way to help u reduce ur heat at the moment is to install a fan temporary to help ease the chiller performance.