Stuart Mueller wrote:

While sitting at a computer Christopher wrote:
In my 125g I have 6 20 watt bulbs, 2 are actinic 03 and four are
powerglow. I was wondering if anyone had any ideas about turning on
(via a timer) the two blue actinic lights say 30 minutes before you
turn on all the lights and leave them on for 30 minutes after the
powerglo's turn off. This could simulate sunrise/sunset.

http://www.thekrib.com/Lights/sunset.html

never tried it but it sounds really good, if you can get the bulbs!

Now there's an elegant solution to no known problem! I wonder if anyone
ever built that?

Back in the real world, I have my lights on two timers, offset by 15
minutes. The fish get a whole lot less jolted when just on bank turns on
(the back bank, which actually lights up the tank less than the front
bank). When all 220 W came on at once, they get perturbed.

I think 15 minutes is plenty. That's also the smallest division on the
timer!