Lighting hours

[buttered loins]

HI

how many hours would you guys recommend to leave your tank lights on

cheers

[Slappy*McFish]

I leave mine on for 12 hrs.

[soccerkidbs]

12 hours with 1 hour actinic before and 2 hours after. i leave moonlights on 24/7

[Charlesr1958]

12 hours, but done so to mimic a "day"

AQUARIUM PHOTO PERIODS : If you are keeping a tropical reef aquarium, it would make sense that your corals and other inhabitants came from a tropical location, which means being near the equator. At the equator, each day light period is roughly 12 hours, each and every day of the year. While it may not seem important to reduce or lengthen the lighting periods, doing such things can pose a risk to your pets. A reduction in the length of the day may not provide enough photosynthesis for the corals symbiotic zooxanthellae, or allow any decorative / functional algae to perform its job of nutrient reduction. A extension of the photo period could also be harmful to the corals over the long term as it has been shown that extended lighting periods can actually be detrimental to coral growth and long term health.
Keeping with an equatorial lighting theme, in my opinion, a combination of lights that will allow you to simulate a sun rise, a high noon intensive period and a sun set would allow for a much more natural environment. To do so, I would have a few compact fluorescent or anything else such as T5 or Power compacts that can be turned on and off independent of the metal halides. As an example of what I would consider a "perfect" lighting system, I would want at least four T5 bulbs or two power compacts and one 250 watt 14,000 Kelvin Metal Halide (one MH per two foot tank length).
Lets say I have four T5 bulbs and a metal halide system, in order to simulate a 12 hour day, I would do the following : (times given are just an example and can be adjusted to your schedule or needs)

7 am - Two of the four T5 bulbs turn on. (or one power compact turns on)
9 am - The remaining T5 bulbs turn on. ( or the second power compact turns on)
10am - The metal halides turn on.
3pm - The metal halides turn off.
5pm - Two of the four T5 bulbs turn off ( or one of the power compact turns off)
7pm - The remaining T5 bulbs turn off ( or the remaining power compact turns off)
The use of a few LED lights for night time viewing is optional here, I prefer not to use them as my tank inhabitants, including the fish, do not exhibit what should be normal dark period behavior with any ambient light being on.
Also keep in mind, that being "tropical" means that every day is not a clear sunny day, there are a great many dark cloudy days and there is nothing wrong with leaving the metal halides or other intensive lighting off for an entire day once a week. Also, if you use any bulbs that are 10,000 kelvin or greater, there is no reason what so ever to also use actinic supplementation. Such use of those bulbs goes back in history when the hobby only had 6,500 kelvin (or lower) bulbs available and to better simulate the kelvin as received by corals at depth, such low kelvin bulbs had to be supplemented with actinics. I am to this day still amazed that with 20,000 kelvin bulbs available, or any kelvin for that matter, we have not broken the habit of using actinics on already too "blue" of tanks. So stop it will ya!, unless of course you are using 6500 kelvin bulbs.

My Lighting Page (http://home2.pacific.net.ph/~sweetyummy42/lights.html)

Chuck

[Catpicklesdog]

I'm unable to run my blues and Halides seperately so they all come on at 10am and go off at 6pm. The moonlights come on at 5.30 and go off about 3.30am.