@TX_Punisher -- You asked "Is T5 your main SPS lighting source?" But you didn't let us answer "no" in the poll. I think that would give us better results.
I'll be honest -- I've been doing this awhile, never once has PAR been an issue for me. I run a 14 hour photoperiod for LED's at 100%, and 10 hours for T5's. I don't think there's a such thing as too much light, unless you have SPS with low nutrients + high light and/or high/low alk.
It’s really helpful to measure your PAR before starting to mess with the photoperiod.
I'll be honest -- I've been doing this awhile, never once has PAR been an issue for me. I run a 14 hour photoperiod for LED's at 100%, and 10 hours for T5's. I don't think there's a such thing as too much light, unless you have SPS with low nutrients + high light and/or high/low alk.