I use both...6' tank lit by a single 20 watt HQI in the middle where the sps reside and the ends are lit by T5's. It works but getting the colors and intensity equal hasn't worked out yet. I need more T5's but the softies are on the ends of the tank and they don't seem to mind. Heat isn't a problem, and the elect. is less. I still believe in halides for sps and doubt that will change. I am sure I'll end up with halides on the whole tank again, but maybe just 150's on the ends and T5 for actintics. I may just sell the thing and blow up pics ot the TOTM and hang where the tank is now...would be so much cheaper. lol