# how long should light be on in a planted tank?



## wkndracer

8hrs


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## Kathyy

With all that light you might raise up the lights and have an even shorter lighting period, maybe even down to 6 hours. I time the lights for me, lights out at 11 PM so I can enjoy the tank at night.


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## 2in10

I am using 8 hours with 2 T5HO bulbs 6" above the tank and CO2 and ferts. With your lighting level you probably shouldn't go much past that. You should look into EI dosing or something similar for ferts; your lights cause your plants to need a lot of ferts to out compete algae. I used to do 10 to 12 hours with 260W PC on my 75. I decided 10 was enough there because it kept algae to a minimum.


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## BBradbury

*Lights on in a Planted Tank*

Good morning wet...

I have several 55 G, low tech, planted tanks and all my plants are the tropical variety and used to long hours of daylight in their natural habitat. So, the minimum is 10 hours. I have my tank lights on timers set for 12 hours on and 12 off. 

I have a lot of my plants in pots because I use organic potting soil and different substrates. You can move potts or stack them to take the best advantage of the light. 

I think it's important to duplicate the natural habitat as close as possible for plants and fish, so longer hours of light seems to work best for my fish and plants.

B


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## Steve001

wetworks said:


> What is the recommended time of light and dark in a planted tank? I just got a timer for my first real planted tank, and I am not sure just how much light I need for my plants each day. I have the following plants:
> 
> Amazon Sword
> Argentine Sword
> Anubias (don't know variety- it was just labeled 'Anubias' in LFS)
> Kompakt
> Wisteria
> Anacharis
> 
> Tank is 38g, lights are 2x39w T5HO, don't have CO2 hooked up yet but I am dosing Excel until I do. Also dosing with Flourish Comprehensive. I was going to set my timer to coincide with day/night here in Florida, but we have 14+ hours of light here and that seemed a bit much. Any suggestions?


With lighting duration it's not complicated. 8 hrs is fine. 10 hrs is fine. 12 hrs is fine. If plants get enough light some will fold their leaves.

My long running tank uses only natural light with all it's variations through out the year. Some days it gets dim light. Some days bright light. Some days direct sunlight. Some days it gets all three in one day. And it does well.


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## nalu86

Steve001 said:


> With lighting duration it's not complicated. 8 hrs is fine. 10 hrs is fine. 12 hrs is fine. If plants get enough light some will fold their leaves.
> 
> My long running tank uses only natural light with all it's variations through out the year. Some days it gets dim light. Some days bright light. Some days direct sunlight. Some days it gets all three in one day. And it does well.


and how do the fish react to the temp changes?

To much or to long light is never good, to much or to long light will activate algae blooms.


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## wetworks

Thanks everyone for your advice. I will set my timers for 12 hours on and 12 hours off and see how my plants like that. +1 for running the lights when you want to actually enjoy your tanks and not trying to duplicate daylight/night-time. I have the option with my light fixture to choose either light, both lights or no lights. Should I vary the intensity of light during the day periods? For instance, one bulb can run continuously for 12 hours, and have both lights on for a six hour period in the middle of the day? I have heard of people doing this for saltwater reef tanks. Am I overthinking this?


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## Rainer

wetworks said:


> Thanks everyone for your advice. I will set my timers for 12 hours on and 12 hours off and see how my plants like that. +1 for running the lights when you want to actually enjoy your tanks and not trying to duplicate daylight/night-time. I have the option with my light fixture to choose either light, both lights or no lights. Should I vary the intensity of light during the day periods?


How high above the substrate and tank are your lights? If you're in a high light situation when using both bulbs, I'd strongly recommend starting out with something like 6-8 hours max. And make sure you have your CO2 dialed in first. Why risk an algae bloom? You can always increase the time slowly until you start seeing problems.

As for variable lighting, I started off with a 2-4-2 photoperiod, which is four hours of high light (both bulbs) with two hours of medium light (one bulb) before and after. Now I'll up to 1-6-1 and beginning to see some warning signs.

Take a look at EI dosing in the fertilizer forum stickies. You're going to need a full range of fertilizers if your lighting is high.


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## Steve001

nalu86 said:


> and how do the fish react to the temp changes?
> 
> To much or to long light is never good, to much or to long light will activate algae blooms.


There isn't a temp change because the tank only receives direct sunlight during the winter months. And it's only for a short duration so no algae bloom either.


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## wetworks

Rainer said:


> How high above the substrate and tank are your lights? If you're in a high light situation when using both bulbs, I'd strongly recommend starting out with something like 6-8 hours max. And make sure you have your CO2 dialed in first. Why risk an algae bloom? You can always increase the time slowly until you start seeing problems.
> 
> As for variable lighting, I started off with a 2-4-2 photoperiod, which is four hours of high light (both bulbs) with two hours of medium light (one bulb) before and after. Now I'll up to 1-6-1 and beginning to see some warning signs.
> 
> Take a look at EI dosing in the fertilizer forum stickies. You're going to need a full range of fertilizers if your lighting is high.


The light is three inches above the top of the water and 22 inches from the substrate. Right now I am running at a hair over two watts per gallon, which I think sits right in the middle of what I have read here is acceptable for most plants without being over-powering. (High light means 3+ WPG, correct?) I am ordering the final components for my CO2 system this week, but for the time being I am using Excel; I am also dosing with Flourish Comprehensive twice weekly. These are the only ferts that are currently available to me as there is not too much here in my LFS and the chain stores carry pretty much nothing. With my plants and my lights, do you have any recommendations for appropriate ferts? Thanks for your help!


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## Rainer

Just a quick note as I'm on mobile now.

WPG is out the window where T5HO is concerned. There is a sticky on the lighting forum which you should check out. At that height, you may be in medium light territory.

As for ferts, the spectrum of chemicals you will need are available from online sources. Greenleafaquariums is one, IIRC.

You'll need KNO3, K2PO4, a micro mix like CSM+ B, and perhaps GH Booster.

Edited to add: looks like you're still in high light according to Hoppy's chart.


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