couple things..
first you want 18 or more hours of light for sure... whether you choose 18/6, 19/5, 20/4, 21/3, 22/2, 23/1, or 24/0 you need to have AT LEAST 18 hours of light to veg.... you can use less but the results will be more than likely less than satisfying...
second what you choose doesnt matter... there are some questions you can answer to help you decide what works best...
1) are temps going to be an issue?? if you know its going to get too warm in the middle of the day to make you feel comfortable you may choose to have a dark cycle in the middle of the day... in which case a 24/0 cycle wouldnt be as good for you as an 18/6 or 20/4...
2) the obvious question of electrical consumption.. we can all stand to save some money on electrcity.. but are the hours of darkness worth the money you save??
3) how available are your nutes to your plant?? i say this because, for instance, in a hydro environment where the plant is constantly feed nutrient rich water. all the nutes it needs to maintain steady prolific growth is available.. but in soil, where nutes have to be broken down to become available to the plant, it is possible that the nutes arent available to the plant as quick or in the amounts the plant needs.. so have a dark cycle, where the plant functions are slowed and nutes are used less, it can give the nutes in the soil time to break down to keep heavy growth for your plants during the light cycle... so a dark cycle in this case would benefit in a round about way.... make sense??
4) how much co2 is available to your plants?? is it going to have a fresh air intake or are you using co2 supplement?? reason this is thrown in is plants use co2 in large quantities... if you know that you wont be able to supply enough co2 to your plant to keep it growing at a steady rate, you might want to consider a dark cycle to allow your co2 levels to rise in and around the grow room so that when the lights are back on and growth starts again , there will be a fresh supply of co2 for them...
i think there are a lot of factors such as those people dont consider when deciding what cycle to run... plants need to have even levels of everything to maintain constant growth... plenty of co2 or fresh air, light, nutes, and water... or at least the amount of any one area will depend on how much of the other areas are available... if you cant keep everything in balance all the time during a 24/0 cycle it can be worth a dark cycle.. the dark cycle would work as a buffer zone to allow everything to even out.. or at least give you a chance as a grower to use time to get things back in balance... i really hope this makes sense.. or that i explained it well...
