# how long do you leave lights on a day?



## gundaman (Feb 24, 2013)

how long do you leave lights on a day? I currently have shrimp (neos and caridina's) tanks and keeping them lights on 11 hours a day, is this too much lighting? thanks


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## Seattle_Aquarist (Mar 7, 2008)

Hi gundaman,

A little more information would be helpful. 
What size tank?
What kind of light?
What wattage bulb(s)?


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## gundaman (Feb 24, 2013)

Hi I have t8 lighting, 64 watts total.


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## gundaman (Feb 24, 2013)

1o gallon tanks.


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## Seattle_Aquarist (Mar 7, 2008)

Hi gundaman,

Assuming the light is close to the top of your tanks, and your substrate is about 2" deep, I would estimate your PAR reading at about 80 which is medium / high light.

At that light level, especially without CO2, it is very easy to get outbreaks of algae. 

I would start with a short photoperiod, maybe 4-5 hours and increase about 1/2 hour per week until algae outbreaks occur. Then back off 1/2 to one hour and see how that works.


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## gundaman (Feb 24, 2013)

thanks seattle, when you say photoperiod do you mean take a break for 4-5 hours or leave lights on for that amount of time? My tanks are well established (6 months+) and I do have a little algae growth but not overwhelming my tanks. I did have algae outbreak in some tanks before but I scrubbed all of it off and a lot of it hasn't came back. thanks.


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## Seattle_Aquarist (Mar 7, 2008)

gundaman said:


> thanks seattle, when you say photoperiod do you mean take a break for 4-5 hours or leave lights on for that amount of time? My tanks are well established (6 months+) and I do have a little algae growth but not overwhelming my tanks. I did have algae outbreak in some tanks before but I scrubbed all of it off and a lot of it hasn't came back. thanks.


Hi gundaman,

To clarify, typically I would keep my lights on for total of 4-5 hours and increase gradually in weekly increments until algae became an issue. Possibly the shrimp are helping to keep your algae in check.


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## gundaman (Feb 24, 2013)

would it cause any stress to my shrimp's/plants if I change their light cycle from 11 hours to 4-5? thanks.


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## Seattle_Aquarist (Mar 7, 2008)

Hi gundaman,

Since you are not having any issues with algae then possibly you don't need to drop the photoperiod down that far. That said, changing a photoperiod would likely cause little stress to the shrimp or plants.


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## gundaman (Feb 24, 2013)

thanks for the input, I did a little google research and dropped it down to 10 hours a day for now. thanks.


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