My theory :

(using (1) 400watt hps and (1) 400 watt MH)

ok so if you think about from about march 20th til september 22, (in the northern hemisphere) days are longer by a small margine maybe a couple minutes. and this would be the ideal time to flower outdoors (outdoors = more yield) eventually if you add it up, doing indoor 12/12 is always the same, outside, flowering is more like, the month, May would be like 12.1hours of light/11.9 hours of dark. July would be12.2hours of light/11.8 hours of dark and august would right about 12.1hours of light/11.9 hours of dark such as may. so technically your lighting cycle is everychanging. also, the intensity of the sun in the first couple hours and last couple hours of the day would be less then what they would be during the day, by comparison(example on 4 plants), running 400watt MH 2 hours, then running a 400watt HPS for 4 hour and turning off the MH, then run the MH for 2 hours and turning off the HPS. then giving the plant 8 hours of darkness.

maybe also, at the beginning of flowering, if using the MH >HPS>MH>Darkness theory, run MH for 2.1hours>hps 4.1 hours>MH 2.1 hours, darkness 11.7 hours. for the first 2 weeks, the next 4 weeks do, hid 2 hours>hps 4.5 hours>MH 2 hours/darkness 11.5 hours. and the final 2 weeks go back to run MH for 2.1hours>hps 4.1 hours>MH 2.1 hours, darkness 11.7 hours, or just 12/12 with hps and darkness.

also i believe kelvin somewhat changes throughout the year, (spring, summer, fall, winter) so i somewhat based the MH/HPS changes off that.

:say in july:
canada grows some amazing bud i hear, and according to this, if outdoor, there is actually about 16+ hours of light each day as apposed to california where there is about 14 or so.
california: http://www.gaisma.com/en/location/concord-california.html
canada : http://www.gaisma.com/en/location/calgary.html

and apparently, canada's days are also shorter in the winter. so the sudden change of day lengths change more dramatically than in the states.

This shows how much day light is given by latitude throughout the year : http://en.wikipedia.org/wiki/Fileay_length.jpeg
This shows a world map and lattitude so you can judge where is what : http://www.satsig.net/world105.gif




As a consequence, for half a year (from around March 20 to around September 22) the northern hemisphere tips toward the Sun, with the maximum around June 21, while for the other half year the southern hemisphere has this honour, with the maximum around December 21.

__________________
My 400/1000watt/outdoor hps shed grow
(prop. 215)

what do you guys think?

__________________
My 400/1000watt/outdoor hps shed grow
(prop. 215)

i think a 400w hps IS a 400w HID (high intensity discharge, mv, mh, hps).

i think hps puts off more of a certain spectrum*than a metal halide*

__________________
My 400/1000watt/outdoor hps shed grow
(prop. 215)

hps is a type of high intensity discharge lighting, or HID. there are others, namely metal halide and mercury vapor.

high pressure sodium is warm spectrum, red/yellow.
metal halide is blue spectrum, blue/white
mercury vapor is extreme blue spectrum, not very ideal for cannabis, or many other plants.

oh, sorry about that, i meant to put Metal Halide. i have 2 400hps and 1 400Metalhalide.

__________________
My 400/1000watt/outdoor hps shed grow
(prop. 215)