My Rastas seem to multiply best at 74 to 75 and if I want a bigger polyp and less vibrance in color I shoot for 78 to 79. For all around best of everything I try and stay at 77. On the other hand my personal Morph Cherry Garcias get better color at 78 but if my chiller screen isnt clean my temp will climb up to 80 to 82 and I notice that the stem gets really long and the actual head of the paly is about 3/4" and some get as large as an inch. Thy are massive