# Adjusting lighting needs



## Fish bone (Sep 7, 2014)

With an El Natural tank I understand the lighting needs to be balanced with other parameters.
So with, let's say, a Fugeray Planted Series LED light, the light is too bright. 
Not being able to dim the lamp, would a shorter on time be as good for growth and algae control?
Or must the 10 to 14 hour on time be maintained and the lamp assembly be better matched?
Matching seems to be a problem because of the lack of data (par, lumen, etc.).


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## BruceF (Aug 5, 2011)

Less time is fine. Try 8 hours to start with. 

Do you have a lot of plants?


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## pandragon (Jul 10, 2014)

I have a finnex planted+ on a 30 gallon tank and 8-10 hours is fine, over 10 and growth slows quite a bit. I have the light sitting on the rim about a couple inches from the water surface. I might get another light later to balance it a bit and will probably have to limit or dim the light, but I think the coverage of one light in back and one in ront would be better than the single light in the middle. If you have any particularly light demanding plants you might want to stick the light directly above them, but other than that I think you should be fine in the 8-10 hour range without a dimmer.


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## TankAaron (Aug 8, 2014)

Longer photo periods reduces growth rate? I did not know that. Today I learned!


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## pandragon (Jul 10, 2014)

Plants use all the available nutrients and co2 when photosynthesizing, no additional co2 can make plants use up what is in the water column, or when there is too much surface agitation and the co2 gasses out of the water. High tech tanks tend to have longer photoperiods with the addition of extra co2 and nutrients to try to balance everything out.


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## Fish bone (Sep 7, 2014)

No plants as yet, but will have a full compliment when set up.
I thought I read where 12 hours should be targeted for plant health.
But your experience with shorter time makes some sense. 
Thanks


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## Michael (Jul 20, 2010)

You could also try a "siesta" schedule: lights on 4-6, lights off 2-3 hours, lights on 4-6 hours. In a Walstad tank, this schedule allows CO2 levels to rebound during the siesta, making carbon available to the plants during the second period of lights on.

I use this schedule on all on my tanks. Some casual experiments showed that it does help with algae, at least some. It also fits with my schedule--I can look at the tanks in the morning, siesta in the afternoon, then the tanks are lit again for evening viewing when I have the most time for it.


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## junglefowl (Nov 16, 2012)

Or you can use some method to raise the light up if you think you have too much light!


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## TropTrea (Jan 10, 2014)

You are correct in the sense that the lighting needs to be balanced to the needs excessive light or insufficient light can be just as bad on either ends of the spectrum. You need to look at it as a combination of intensity multiplied by time. so if you have 100 units of lights applied for 12 hours you should be simular results with 150 units of light over 8 hours. But there are other factors that also play into the equation. In the event your plants can only absorb and use 120 units of light then the 150 units of light can be less effective than if they were on for 10 hours. Actually if the intensity is too strong the plants could actually be burnt from the excess. 

On the other end of the spectrum if the plants can ideally use 120 units of light most efficiently then giving them less than 96 units or more than 150 units will mean that they are using the total available amount of light less efficiently. 

You also have another factor being the cycle of the plants that includes respiration as well as photosynthesis. Plants need time for both of these processes and generally an equal amount each day. You can jungle the numbers slightly but when you do to much of an extreme the plants will end up being harmed by the lack of time on the other end of the spectrum. 

Finaly in an aquarium with multiple different plants we also find ourselves compromising the lighting needs of one plant to better meet the needs of another plant. So with a shorter time plant A might grow better while plant B might slow down.


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