Plants need their dark period to convert the chemicals they have absorbed in the light period (i.e.anorganic COĀ²) into organic molecules that helps the plant to grow (The Kranz anatomy). This is called the CALVIN CYCLE.

This means, the plant converts chemicals and renews it'sself with help and sythese of those chemicals.

That's why I always use a 18/6 cycle for VEG. I've tried 24/0, but I've found the plants have less stress and look healthier when you give them their dark periode and opportunity to preform their CALVIN CYCLE.

Source: www.vc.bioscience.ru.nl

Greets Britewire