I have now shortened my halide duration to 7 hrs/day (down from 10 hrs per day) with no ill effects that I can see, In fact, I'd say that growth has accelerated but of course that is very subjective. I have also been selling large colonies so maybe there is less competition for calcium and nutrients. But certainly no harm has been done. I will soon shoot for 6 hrs. per day. I do still keep my vho's on for about 11 hrs but may soon knock that down some. I have noticed some (not huge) savings on my NYSEG bill.