24/0 is a waste of money, tho with t5s not a big waste. 18/6 is more energy efficient and works just as well if not better, some people say the plants like to sleep, but ive seen 0 growth rate differences between the two times. The only time I i use 24/0 is revegging plants and when a plant is super sensive and shows flowering traits under 18/6. I had a pineapple express plant that would start to flower under 18/6, but would stay vegged under 24/0, it didnt last long wasnt a great plant...