What T-5 bubs are you running?
I have been testing various LED setups for over a year now in different tanks. My conclusion is that it is changes in spectrum that is responsible for bleaching, not intensity. For example, I just replaced my T-5 supplemental lighting, on my 93g, with a SOL blue. No bleaching and I'm running it around 80% (started at about 70% increased over a few weeks). IME, any bleaching when changing to LEDs is due to the change in spectrum, rather than intensity. The T-5s I was running were very blue, 3x ATI Blue+ and 1 purple+. So, I think even though the PAR is much higher with LED, it didn't matter, because the corals were already adapted to the blue dominant spectrum. This has generally been my experience with LEDs. Moving corals from under my phoenix 250W 14000K, to LEDs has never resulted in bleaching. If you look at the spectral plot for the Phoenix though, the Phoenix has most of it's output in the 450nm range, as do the LEDs. I did have some corals bleach when I went from a 10000K MH to wimpy little PAR30 bulbs in a different tank. Even though the MH had a lot more PAR, the spectral difference was much greater. So, i haven't seen any real relation to intensity (PAR) and bleaching, rather the relationship seems to be spectral output.
I also think some people corals bleach because they run the LEDs too low initially, as they are afraid of bleaching. It is actually possible to bleach corals due to too little light, especially if nutrients are relatively low.
