Originally Posted by Dustymac
Here's an update after six weeks...
In the 55 gallon NPT, the one which gets some sunlight, there was one significant change after initiating a 4-hour afternoon siesta: the Corys stopped spawning completely. Plant and algae growth seem about the same as far as I can tell. Ten days ago I stopped the siesta and the Corys started spawning again. Weird.
I don't know if it's relevant, but my corys always spawn at dawn and a little after. Perhaps having two photoperiods confuses them?
In response to the much earlier post from the fellow who asked about having several siestas in the day: I don't know what it would do for or against plant growth, but it would be terrible for your lights. The hourly rating on fluorescent and metal halide lights assumes a certain number of hours of continuously on operation (at least 3 hours). If you use shorter 'on' periods than that, then you are turning the lights on and off more often than the specification considers and your light bulb life will be shortened to less than the published bulb specification.
In other words, turning your lights on and off shortens the light bulbs' lives. It's probably worth it for one siesta per day. More than one...well I guess it's a personal decision based on your pocket book.
Using the siesta method certainly seems to reduce algae in my tanks. I have two 39 watt 6500K T5 HO bulbs on each 30 gallon (12" X 36") tank and without the siesta algae gets to be a problem. It's still an annoyance, but it's not threatening to crawl out and eat Tokyo.