Plans For My First Grow....

Well, after thinking this through I believe it would be best to do a winter time grow in my area. So between now and about October I plan to get all my equipment, and have a mock grow or two. Sounds like a plan huh?
I already know i an going with the one reflector i priced that has the two 4 inch outlets on it, one on each end. To each I am installing an exhaut fan channeled to the outside. My lighting is going to be 400 watt MH, I will veg with the blue and flower with the red bulb...is that right?
Now comes the tricky part....all the timers I have seen measure the time...this is not what i want though. I want a timer that starts one event and counts the hours that pass at which time the second event is started then counts another amount of hours then repeats. This way, I am not fixed to a 24 hour day, for one thing, and my events do not start at a specific time of day. I found an "Event Delay Counter" that will do exactly what I described, and this no longer ties me to a 24 hour day....I am planning on a 15 hour day once i flower. 9 hours of sunlight and 6 hours of darkness.
I will have a draw fan to bring fresh air into the enclosure, which will measure 5 ft wide X 4 ft high X 4 ft deep=80 cubic ft.
Lastly, I will have my temp/humidity monitor & PH tester and CO2 generator.
At this point, I plan to have a mock grow but rather than growing the real thing, since i have to watch this very carefully, I figure I'll grow some regular plants like spices. If there are major problems that should be revealed during this mock run ... do you think that is true? I understand there will be things unique to weed itself, but major problems are probably common to plants in general.
I will be mixing potting soil with peat mosss & somewhat chunky sand. about 5% sand to 65% peat + 30% potting soil...sound good to ya?
when i do actually grow in October i plan to veg for 45 days...is that too long do you think for that enclosure. I am only going to do about three plants because of testing the length of the day I defined above. I want to eventually test different days/nights on the weed and post those results here for others who may want to see / use those results.
I do think also that by the time October comes along I should have at least one good carbon filter...don't ya think?
If there is something here I am missing, can you let me know, I really am trying to avoid "Major" problems...yeah I might end up with infestation problems but that is fairly handled easy....the co2 will take care of that if it happens.
Anyone have any suggestions just let me know.
Thank you in advance one and all.

r u sure those short days will work?? ive heard of folk doing like 15 hours on, 12 off but 9-6?? will this work?? anyone know?

9/6 probably will not be sufficient. You need to give the plants at least 12 consecutive hours of light for it to work... at least that what I know.

You got a timer to handle that?

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