# How long are you supposed to keep light on in tank?



## ruby716 (Feb 24, 2011)

Hi everyone, I have a 2.5 gallon tank, and was wondering how long I should have the light on for. I had the tank for a little over a month already, and about 3 1/2 weeks into the filter, it turned bright greenish which is obviously algae. It didn't affect my ammonia or nitrite or anything, but I was wondering if it's bad that the filter media changed that color. I just changed the filter about 5 days ago, and it has bright green on it again. Is that bad? I usually leave the light on for about 12 hours a day.


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## GwenInNM (Feb 2, 2011)

ruby716 said:


> Hi everyone, I have a 2.5 gallon tank, and was wondering how long I should have the light on for. I had the tank for a little over a month already, and about 3 1/2 weeks into the filter, it turned bright greenish which is obviously algae. It didn't affect my ammonia or nitrite or anything, but I was wondering if it's bad that the filter media changed that color. I just changed the filter about 5 days ago, and it has bright green on it again. Is that bad? I usually leave the light on for about 12 hours a day.


I don't know much about algae, as I've been lucky not to have it yet. Do you have live plants? 12 hours is too long to leave your light on. I think 8-10 hours is sufficient, much more and you'll get that green stuff. I don't think it will harm anything, and removing your filter will only make your tank go into a mini-cycle. Rinse your filter in tank water and put back, rather than replace.


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## sik80 (Mar 16, 2010)

What filter do you have?

Also, do you have live plants in the tank?

How many fish?

Algae can appear for a number of reasons, excess light being one of them. I'd reduce you light to 8-10hrs per day - if you don't already have one get a cheap timer plug from a hardware store, which allows you to set the time the light goes on and off precisely.


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## Romad (Jun 28, 2009)

+1 on the timer. You can do 4 hours in the morning and then 4 hours at night.


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## Christople (Sep 7, 2010)

GwenInNM said:


> I don't know much about algae, as I've been lucky not to have it yet. Do you have live plants? 12 hours is too long to leave your light on. I think 8-10 hours is sufficient, much more and you'll get that green stuff. I don't think it will harm anything, and removing your filter will only make your tank go into a mini-cycle. Rinse your filter in tank water and put back, rather than replace.


But shouldn't people change the carbon? and the big media.


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## stevenjohn21 (Dec 4, 2010)

I dont use carbon unless i have treated my tank and im wanting rid of the meds. Carbon lasts about 3 days if your lucky so its not worth it. I just stuff filter floss and bio balls in my canister filters and for my HOB filters i make them myself and stuff with filter floss.


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## Christople (Sep 7, 2010)

really/ I have always wasted money on carbon. I put it in every month.


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## ruby716 (Feb 24, 2011)

2.5 gallon, mini bow filter and cartridge, 15 watt bulb.. 2 fancy tail guppies & 2 white cloud minnows and 1 ghost shrimp

i changed the filter once so far but i cleaned it off first and soaked it in aqaurium water b4 i changed it


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## Byron (Mar 7, 2009)

Christople said:


> really/ I have always wasted money on carbon. I put it in every month.


If there are live plants in the aquarium, you do'nt need carbon. Carbon will remove some trace elements that the plants can better use. Also, live plants do a better job than carbon on the bad stuff too, they can take up toxic substances.

Carbon may have a purpose in non-planted tanks, although there are many knowledgeable members here who would even say no to that. A balanced fish/volume level, regular good maintenance, not overfeeding--nature should then be able to take care of things herself.

Byron.


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## ruby716 (Feb 24, 2011)

I don't have any live plants... you can go on the photo and video part of this site and see my fish and tank


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## ruby716 (Feb 24, 2011)

its an aqueon filter too


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## Byron (Mar 7, 2009)

ruby716 said:


> I don't have any live plants... you can go on the photo and video part of this site and see my fish and tank


First off, ruby716, I think this is the first thread of yours to which I have responded, so welcome to Tropical Fish Keeping.

Now to your light issue. I am assuming there are no live plants in this aquarium, in which case light is solely needed for your viewing pleasure. Fish do not need light, ordinary daylight in the room will suffice them, but viewing is nicer with a light. Restricting the light to your normal viewing time will solve this problem. It is, as someone suggested, preferable to have a timer so the light is consistent. Though this is of less significance without plants, still it is advisable. Fish like regularity too.

Algae is a plant, and like all plants it needs nutrients in the presence of light. Unlike higher plants, algae can use any light, even very little, to grow, and there will always be nutrients in a tank with fish. Live plants grab nutrients faster than algae can, provided they have adequate light to photosynthesize, which is why we say that having live plants can reduce or even prevent algae, at least from being troublesome. And "green water" is certainly troublesome.

Hope this helps your understanding of what's happening in that little eco-system.

Byron.


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## Christople (Sep 7, 2010)

what is green water


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## Byron (Mar 7, 2009)

Christople said:


> what is green water


Not sure why I mentioned green water, got a bit mixed up I guess, the initial issue was a green filter. Both are algae related.

Anyway, to answer what it is, it is unicellular algae so proliferous that the water is green, and can be so thick that it is impossible to see into the tank. Like pea soup, literally.


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## Christople (Sep 7, 2010)

Thats nasty.


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## ruby716 (Feb 24, 2011)

Byron said:


> Not sure why I mentioned green water, got a bit mixed up I guess, the initial issue was a green filter. Both are algae related.
> 
> Anyway, to answer what it is, it is unicellular algae so proliferous that the water is green, and can be so thick that it is impossible to see into the tank. Like pea soup, literally.




lol pea soup.. well my filter has greenish on it but my water is crystal clear... is it bad though that the filter is green since water is getting pushed through there back into the tank?


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## Christople (Sep 7, 2010)

It should be okay


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## redchigh (Jan 20, 2010)

yep, the green algae on items is actually a different species than the green water algae.


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