I've been looking at some of the automated aquarium lighting systems that turn on and off automatically at certain times of the day (and even mimicking the gradual change of sunrise/sunset).

But these systems always seem to be based on a timer.

Is there a system that follows the seasonal changes (the changing times of sunrise/sunset throughout the year)? Either an algorithm that mimics the approximate progression of sunrise/sunset throughout the year, or a sensor that actually detects the ambient light levels would be okay.

Apart from any beneficial effects for the fish, it would be nice not to have the lights turning on before the crack of dawn or turning off at 5:50pm (in the middle of the day) because I haven't reset the timer since last December.

  • This question is kind of on the scope borderline for pets, it seems to asks for solution and a 'system' (or product). A solution is provided in the answer below, @Zaralynda is often in chat so you might pop in to The Litter Box to ask about specific products she used. – James Jenkins Aug 21 '14 at 11:03
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    @JamesJenkins Ah, it's fine, Robert's question is narrowly-scoped enough to avoid the actual problems that typically plague overly broad product recommendation questions. Asking for advice on what to use is okay provided that your question isn't simply too broad to begin with. "What's a good aquarium lighting system?" - Bad. "What aquarium lighting systems mimic the natural progression of the sun and optionally work from ambient light?" - Good. In fact, there can't possibly be more than half a dozen valid answers to this, and too many answers is the root of it. I'd say this is fine. – Tim Post Aug 21 '14 at 13:18

I know something about this subject because I've tried to find a lightswitch (for my home office) that does the same thing. I have tried two different timer wall switches that say they turn on at dusk (you have to enter your approximate latitude). We end up resetting them every few months anyway because the clocks they apparently put into such things aren't very good and drift over time.

If I was serious about setting up such a thing, I would use a Raspberry Pi to ask my router what time it is (or an internet timeserver, or something else disciplined to a good clock), then program in sunrise/sunset times at my latitude (or find a site for the Pi to ask), and attach that to a switch. But then, the way I program a Raspberry Pi is "Honey, can you make me a Rasberry Pi to do XYZ?" so your mileage may vary.


Easy way.. buy a dawn to dusk photo cell. Wire it to a relay. Normal switching for photo cell porch light. On at dark, off at dawn. Relay on at night cuts power to your lights. At dawn relay off send power to your lights. No timer to set.

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