Tank lights

[georgia]

I've heard that the tank lights should be on for around 12 hours, and so have now set ours on a timer. Does it need to be 12 hours solid, or can you break it up into 2 lots of 6 hours etc? I'm guessing turning the lights on and off too much might stress the fish out??
thanks
georgia

 

[breezer40]

The lights represent day and night and may confuse the fish so IMO i would leave then on for 10-12 hrs.

 

[B75]

It also depends on wether you have live plants or plastic plants in your tank. If you have live plants then it is recommended to have the lights on for 8 - 12 hours, If you have plastic plants then I always used to put them on for about 6 hours during the day and a couple of hours in the evening when its just getting dark outside.

 

[cometcattle]

If you don't have live plants, I would not recommend keeping the lights on 12 hours unless you want algae.

I keep the light my un-planted cichlid tank on for about 6 to 7 hours a night.
On my planted tanks, I keep the lights on for about 10 to 12 hours a night.

Yes, turning the light on and off could stress your fish, but I've read on plant forums where people with planted tanks do 6 hours on, and 6 off to combat algea.

IMO, it stresses the fish to go from the bright tank lights, to pitch black. I like to leave the room lights on for about 15 minutes or so, after I turn the tank lights off.

 

[pahansen]

Hi. I think that the 12 hour rule of thumb comes from the fact that most tropical fish are used to near-equatorial conditions (12 hours of light, 12 hours of dark.) I have done a variety of things with lights. A lot of it depends on the strength of the light as well.

If you have a non-planted tank, then you can pretty much do what you want, although your fish will appreciate at least 6-8 hours of light a day. If you start to get algae everywhere, reduce the length of light to see if that helps (and make sure your tank isn't sitting near a window). Many commercially bought aquarium hoods do not have a strong enough light to cause major problems with green algaes unless you leave the light on for very long periods. Lessening the lighting period should do the trick.

If you have a planted tank, you will need to have enough light to provide for the plants. Most people recommend 10-12 hours. If you find that your plants are dying, you probably need brighter lighting.

If you have my problem, which is too-bright light in a planted tank, that's where the fun begins. To alleviate algae problems, I bought some different, better-suited plants and changed the light to two five-hour periods a day, with a four hour lights-out period in between.

While my goal is to work back up to one long period of light again, the tank is now crystal clear and the fish don't seem to have suffered in the least. I've been doing this for almost a month now. (The theory is that plants don't mind the break in light, but the algae does.)

I would say that there is no problem with having a long period of light and then a shorter one later, should you want to enjoy your fish before bedtime or somesuch. Since you are using a timer, that is easy to set up. Just keep an eye on your fish so you notice if there are behavioral changes. Let's face it -- some fish are much more sensitive than others.

As for sudden changes in light and dark, I agree that this could be a shock to the fish. During the daytime, at least, your room will probably have ambient light in it already -- few rooms are pitch black in the daytime. At night, you may want to follow cometcattle's suggestion if you are concerned about stress.

Good luck,
Pamela