I was perusing the net, lots of info out there. I found this interesting. Someone put a lot of work into figuring this out, but it seems incomplete. Its a lot of info, grab a cup of something warm take a toke and read.
Manipulate the photo-period
Plants use light to fuel growth. If they receive less light they will grow less. Changing the light/dark light cycle to 10/14 from 12/12 reduces the amount of light the plants receive by 1/6, or 16%. Cutting the light cycle while flowering results in less total growth, because the plant produces less material used for tissue building. Another effect of cutting the light cycle is to hasten the ripening of the plant. By reducing the light cycle during the growth part of flowering, the growth time is reduced.
However this is not a productive trade-off. Not only is the total time under light reduced, so is the percentage of time with light. The yield of the lower light-cycle bud will be more than proportionately lower than normal. However, during the last 10 to 15 days of flowering the bud has little growth. Instead it transforms as the stigmas dry, the ovary behind them swells and the glands fill with THC. Reducing the light period during this time will hasten ripening without significantly reducing yield, by giving the plant a clear signal that the time has come. There are occasions when it may be more important to speed up ripening than to maximize production. Under these circumstances, a 10-hour light/14-hour dark cycle would indeed be better.
The only photo-period manipulation from years of experiments that offered discernible improvements was the following photo-period adjustment made for 1 or 2 calendar weeks at the point of maximum flowering rate: Day length of 21 hours, 36 minutes with a dark period of 12 hours. To accomplish this, you need a 7 day, 24 hour digital timer. During a 7 day calendar week on Earth, the "sun" only cycles 5 times. This permits easily switching back to the regular 12/12 at your discretion. You may want to only alter during peak flower production to stimulate the plant's metabolism. Using this photo-period throughout the flowering cycle will cause this:
A variety that takes 49 days of 12/12 to mature, won't see 49 — 12 hour dark periods under 21:36/12 until almost 10 calendar weeks have passed.
The total increase in light energy is almost 80%, which will produce larger yields, if all of your other environmental conditions are kept optimal.
The total increase in flowering period is only 40%, half the potential room for improvement. This means you don't have to be perfect to win out.
Selective application of the 21:36/12 photo-period for only 1 or 2 weeks extends the wait only 2 to 4 Earth days, which makes up the missing 2 complete day and night cycles each week on Planet Ito. This permits the additional light energy to be provided without purchasing additional equipment or overloading existing circuits, which maximizes the existing system's capabilities. The main advantage is that matched with co2 and optimal nutrition, the plants metabolism will increase dramatically. I have only successfully tested this photo-period for two weeks. The potential for a net increase of 40% over the entire cycle (80% increase in light energy vs. 40% longer wait) is worthwhile.
Day 1 — Sunday, 6:00am til Monday, 3:36am Day 2 — Monday, 3:36pm til Tuesday, 1:12pm Day 3 — Wednesday, 1:12am til Wednesday, 10:48pm Day 4 — Thursday, 10:48am til Friday 8:24am Day 5 — Friday, 8:24pm til Saturday 6:00pm
. Thank you all for helping make this site my favorite. Seriously a 13 strain joint, heh. 
I will have to read it again later
Rock on Smoke2Js
If you sprout it they will come.
. When I get my LED grow gowing I will do a side by side, but thats a few seasons down the line. Until then somebody else might try it. It would be intersting to see. 
