Lighting Timer Question

Hello,
I've just setup my new 180gal 6ftx2ftx2ft plant tank. I went all out with this one. I've got pressurized CO2, automatic water changer, dosing pumps etc. Now I'm not sure what the best settings for my light timers should be. I now have the ability to do something new and that is stagger the lighting throughout the day for the sunrise/sunset effect.

For lighting I have a combo MH and PC fixture from Hamilton Technologies. The fixture is 6ft long (same as the tank). It has a mirror finish reflector. It has 4 power cords that are pluged into seperate timers, and is suspended from the ceiling about 12inches above the tank's glass top.

The first power cord controls 2 65watt PC bulbs located on the rear lefthand side of the fixture.
The second power cord controls 2 65watt PC bulbs located on the front right hand side of the fixture.
The 3rd power cord controls 2 175 watt MH bulbs located left and right side of the fixture and the cooling fans.
The 4th power cord controls 1 175watt MH bulb located in the center of the fixture.

Now here is what I've been considering. Setting the 2 175watt MH bulbs to come on for 8hrs during the middle of the day, with the third 175watt bulb to come on for 6hrs approx an hour later and turning off an hour before the other two. I would have one of the sets of PC bulbs come on about 2hours before the 2 MH bulbs and turn off 1 hour after they turn off. I would also have the other 2 PC bulbs come on 1 hour before the 2 MH bulbs and turn off 2 hours after.

So if I figured this out right I would have:

9:30am - 10:30am = 0.7 watts per gal (130watts total)
10:30am - 11:30am = 1.4 watts per gal (260watts total)
11:30am - 12:30pm = 3.4 watts per gal (610watts total)
12:30pm - 6:30pm = 4.4 watts per gal (785watts total)
6:30pm - 7:30pm = 3.4 watts per gal (610watts total)
7:30pm - 8:30pm = 1.4 watts per gal (260watts total)
8:30pm - 9:30pm = 0.7 watts per gal (130watts total)

9:30pm to 9:30am = 0 watts per gal (12hrs of night). There would probably be about 4hrs during this time where the tank would receive ambient room light, but it should still get about 8hours of complete darkness.

Does this sound reasonable or would a different arrangement be better? Ideally, I would like some light on until at least 9:30pm so that I can check things out and feed the fish when I get home from work, and have the lights come on as early in the day as possible so that I can see to to maintenance on the weekends without having to wait til later in the day to be able to see what I'm doing.

 

Re: Lighting Timer Question

Just checking to make sure I understood what you were suggesting. You suggest that I move my brightest lighting period to 2 hours after lights on and for a duration of only 3 hours instead of 6 hours. And you also suggest that I shorten the total tank daylight time to 10hrs instead of 12hrs.

The part of moving the brightest part to the beginning of the day makes good sense to me. I was planning on having the automatic water changer run then the dosing pump run just prior to lights on, figuring that this would ensure that the plants had optimal conditions when the lighting period starts with minimal excess during the dark period.

The part about shorting the bright light period that drasticly puzzles me a bit. Just seems like it would be too short. Any chance you can expand on this part? I will rely on your wisdom for this, as it is my first high light tank.

Would there be much harm in extending length of the dim light period, or will that cause me more trouble than its worth?

Thank you very much for the advise!