Quote Originally Posted by harris7
plants grow fastest at 24/0- Ed Ros. Did studies on this, he found a linear curve in growth vs photoperiod hours.
Plants may flower at less than 18/6 depends on strain

you dont want to change your photo period as little as possible. Your plant has a cycle which it likes to establish based on the photoperiod. So if you change the period the plant must change it'd cycle and it dosn't like to.
i can speak for big ED ,all i know that i have less problems with my plants when i use 18/6. also a plants root system grows better with a dark period and in my book healthy roots mean healthy plants.