Varied lighting periods
Just my two cents as I read this same advice (ref below) and do this for the following reasons.........
off: 3-6 pm
off: midnight-9 am
1. Ability to view the tank later at night (after work/excercise/etc) and still have a 10-12 hour photoperiod due to the 3 hour time off period. Remember, we keep fish/plants to enjoy watching them!
2. Fish have period in mid-day with natural light only. I have many cardinals and they especially seem to enjoy schooling in the upper reaches during this time. Mid afternoon light is strongest in my apt, so the timing works well. A little direct sunlight gives the tank a nice shadow/light pattern that is very pretty at this time as the sun moves across the sky.....
3. Reduce heat a bit during mid-day (MH lights are hot and so is S. FL), even thought lights have builtin fans. I have noticed a slight drop in temp during this time (80.1 - 79.2) that does not occur with the lights on during this same period (did not always have this pattern and I compared bef/aft), so assume this does in fact make a slight difference.....
4. Matches South FL weather patterns by having off period from 3-6. You would be amazed how many times a week it rains during this exact time frame, you can set an alarm by it
Reason author gave that I read (and as I understood it) was that algae take longer to begin assimilating nutrients/c02 than higher plants after the beginning of a photo period. Thought was that this would put the algae at some slight disadvantage and allow the plants to access the nutes first.
Reference: Peter Hiscock, Encyclopedia of Aqaurium Plants (2003), pg 59 (siesta periods)
Not sure if this is true or not and certainly defer to the experience/wisdom/knowledge of others, but the other benefits above work for me and my setup
. My plants seem to suffer no ill effects that I can see doing this and have had many species at var times.....
Just wanted to add my experiences to this thread/discussion.
Thanks and have a great day!