# how long do you leave light on



## guy123 (Dec 18, 2006)

is it ok to leave on 24 hours


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## Laith (Sep 4, 2004)

No.

Not having any details of your setup I'd say between 8-10 hours max.


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## eklikewhoa (Jul 24, 2006)

What Laith said unless you are trying to grow algae.


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## bristles (Mar 7, 2006)

24 hour photo period will eventually kill the plants. they need a rest period, a 8 - 12 hr photo period is best for photosynthesis.


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## freydo (Jan 7, 2006)

trust me, definitely not 24 hours. i had a timer bust on me and kept the lights on, and because i was house sitting for a week, i didn't realize. the results were lots and lots, gobs and gobs of algae.


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## Jason Baliban (Feb 21, 2005)

Remember your 10th grade biology class

There is a dark cycle to photosynthesis.

jB


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## subundaortus (Jun 17, 2006)

I use the "siesta" method. I run my lights for approximately five and a half hours, then a two hour siesta, then lights back on for another six hours. I have never had a problem with algae.


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## rhodophyta (Jan 23, 2006)

I grow Daphnia with 24/7 light so that it doesn't "hibernate" in the winter months. While it's true that some algae do well in 24/7 light, not all do. The soft hair algae does well which is a treat for plant eating fish or for shrimp. Duckweed and Najas prosper in 24/7 light. Predictable.  Riccia, Fontanalis, and Monoselinium do well in it, and Rotala rotundifolia and Hygrophila pieces get in the tanks and grow well until I fish them out when they get too much in the way.


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## ruki (Jul 4, 2006)

As the last person stated, It depends upon the purpose of the tank.

If you are trying to maintain green water for daphnia 24*7 makes sense. But, I can keep green water green with only 12 hours of light, so why waste the electricity 

My T5 HO TekLight creates an algae mess when it's on for more than 8 hours. My medium light tanks do well with 12 hours.


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## rhodophyta (Jan 23, 2006)

ruki said:


> As the last person stated, It depends upon the purpose of the tank.
> 
> If you are trying to maintain green water for daphnia 24*7 makes sense. But, I can keep green water green with only 12 hours of light, so why waste the electricity
> 
> My T5 HO TekLight creates an algae mess when it's on for more than 8 hours. My medium light tanks do well with 12 hours.


I was not maintaining green water with 24/7 light, but daphnia. In the winter if you shorten the photoperiod, daphnia can go into a resting mode. Instead of 100% females all giving live birth to clones of themselves, you get 99.75% females with that little one male in four hundred impregnating all the females who then produce resting eggs and die. He is not your friend if you want to raise daphnia. If you are culturing green water, the 24/7 makes sense there too. You get at least twice the production of a 12 hour cycle, so you only need half as many cultures and half as many lights.

I think it makes sense to use a 10 12 hour cycle on a planted tank. The plants I mentioned just happened to end up in a daphnia tank. If possible it would seem like having the lights on a staggered timer so that one then two lights are on and then drop back in reverse order. If this happens to create a light pattern mimicking the path of the sun, so that the light proceeds over the day from front to back, that might be useful. It certainly makes sense to periodically adust the lights so they are not over the same spots all the time.


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## Gary42 (Feb 18, 2006)

I'am with the guys who leave their lights on for about 5-6 hours to keep the algae down. I still get the string algae but have been able to keep the hair algae down to a minumum. I invested in timed powerstrips to not have to worry about how long the lights have been on. Learning all you can about ferts will save you on lot of frustration too.
Just my two cents worth


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## rhodophyta (Jan 23, 2006)

Yes, timers are great. No matter how disciplined you are, it's not easy to be as perfectly consistant as the timer. It is not a bad idea to have a timer on each light on the tank that has an individual cord. That way you can go from one light to all the lights on and then stage back down. I keep hoping to find an after Christmas sale on all the outdoor Christmas light timers, so I have not reached that ideal yet either.


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## ruki (Jul 4, 2006)

re: Christmas lighting parts for aquarium timer use

I would generally recommend against this. Much of the Christmas tree lighting gadgets are generally very flimsy, in part because they only have to be used for a short time period. Also, they don't always clearly rate how much power they are rated for, and I don't really trust it when they do  The savings from using such, ahem junk, are not really justified in the end. (why use stuff that doesn't last very long and may start a fire)

What I have done is use a heavy duty 3-prong timer with a power strip plugged into it. Most hardware/home stores will have these. It's not all that expensive and 9 times out of 10 are much more rugged than Christmas tree light gadgets providing the same function.

I have also used the heavy duty electric hot water heater timers (the ones in the metal box) when I get tired of replacing the mechanical timers after 12-36 months. This is probably over-kill for most folks. Digital timers tend to get zapped, so I can't recommend thost at all.

Taking this a step further, I screw the power strip into the aquarium rack, above the water line, and then trim the cord back to the ideal length and attach a super-heavy-duty connector to shortened cord to plug into the timer.


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## rhodophyta (Jan 23, 2006)

ruki said:


> re: Christmas lighting parts for aquarium timer use
> 
> I would generally recommend against this. Much of the Christmas tree lighting gadgets are generally very flimsy, in part because they only have to be used for a short time period. Also, they don't always clearly rate how much power they are rated for, and I don't really trust it when they do  The savings from using such, ahem junk, are not really justified in the end. (why use stuff that doesn't last very long and may start a fire)
> 
> ...


I haven't looked at Christmas tree light timers, so you are probably right about them. I was looking at the outdoor Christmas display timers which look quite sturdy. When we originally built our 40' x 14' fish room, we installed a 20 amp light circuit with a built in timer next to the circuit panel. It controlled power to the right side of four gang outlets in the fish room. It worked for about ten years, but then I began using individual timers on some lights so that the lighting would come on at staggered times instead of all at once. That circuit timer does not reach the display tank in the livingroom, so I would still need more timers anyway.


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## ruki (Jul 4, 2006)

All this stuff does add up.

One thing about the plug-in-the-wall timers. I was at Lowes and noticed that they had Westek 3-prong timers. Cheaper than Intermatic and had seveal differences in the design:
* It takes up less outlet space. Better for crowded outlet strips.
* plastic door covers timer wheel, looks better.
* permanently mounted tabs, every 15 minutes for multiple on/offs, probably need a needle nose pliers to toggle them though.

Don't know how long it will last compared to Intermatic.


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