[APD] Re: Lighting -- How many hours in a day?

[Bill Wichers <billw at waveform_net>]

> I would like to stretch out he evening hours so that I can feed the fish at
> 8 AM and still have time to view them in the evening.  If it was reasonable,
> I'd like to have 14 hours of 110 watts on, plus 4 hours of both banks of
> lights on, near noon. Each set of lights will be slightly different, so one
> will probably be dimmer than the other, one being 6700K from PSL, the other
> the GE 9325K bulb. I read recently that doubling up the light during the
> day, as in one bank on at 8 and the second bank on at noon, with staggered
> off times, might actually benefit the algae more than the plants.

I used to run a few of my tanks on 14 hour light days. I didn't have any 
trouble doing that, although I run 12 hour days now. I changed a lot of 
dosing routines and such around the same time so it's hard for me to say 
for sure what effect the light change alone had on the tank.

> Does anyone have any advice to offer? Should I limit the total span of hours
> to 11 or 12 hours, or is 14 OK? Is it OK to increase the light near noon for
> awhile? Is there any wisdom in starting the lights together for 9 hours,
> then shifting one to delay on and off? Or would starting with one bank of
> lights only be wiser, then adding the noontime lighting in increasing
> amounts?

12 hours is the usually quoted day length for tropical tanks. Adding an 
hour shouldn't be any problem. If you overlap some lighting you should be 
fine, although I would bring in the longer day gradually -- that is don't 
switch from 12 hour days to 14 hour days in one day. Sudden changes are 
what always cause problems in my own tanks, but the same change made 
gradually over a few weeks or months usually isn't a problem.

> I am pretty nervous about starting off badly with this tank, as it is in the
> den and with the holidays coming, I fear that it could be a huge mess right
> as company comes to visit. I'm planning to test the lights and CO2 before
> [snip]
> Ann Viverette

If it's a new tank you'll have less to worry about since you won't be 
disturbing an established tank. Algae blooms have always happened quickly 
when I mess up lighting in my tanks, so if you do do something your tank 
doesn't like you should know quickly enough to make a change before you 
have people looking in your tanks. The gradual dawn/noon/dusk/night cycle 
is a neat way to run a tank, IMHO. Not sure if the inhabitants really care 
all that much though either way.

        -Bill


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