# Does using a moon light / blue light in the evening cause algae?



## fishbro (1 Dec 2018)

Hey guys, so I have been trying to think of ways to control my algae problem lately. I am getting a combination of several types, most commonly dreaded BBA...

Right now I am using an 8 hour photoperiod (which is 7 hours full intensity with 30 mins on each side for sunrise/sunset) and then after sunset it is running low intensity blue light for about 4 hours in the evening.

The lights I am using are Eheim PowerLED+ Fresh Plants https://www.eheim.com/en_GB/products/technology/lighting/powerled-plus/plants-lk1-771mm

I have two of them to replace the original T8 tubes in the tank, along with the controller (which is how I set just the blue channel to run in the evening)

Would the blue lighting in the evening be contributing to the algae issues? I'm going to shorten the main lighting period by an hour to see if that helps too.


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## Barbara Turner (1 Dec 2018)

I would guess that your algae will still manage photosynthesis with just blue light.  With the equivalent of 12 hours light, I bet the algae is doing quite well.  The only thing you might want to try is green/ yellow light.


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## Zeus. (2 Dec 2018)

Plants  need a certain amount of light (PAR) to be able to use it, but algae can use light at mich lower PAR levels and still thrive. So having low intensity lighting for several hours for extended viewing is giving algae a chance.
We should aim at healthy growing plants and we wouldn't use very low intensity light for that.

I also have an extended light viewing for about 40mins but not every day, once a week twice tops.


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## fishbro (2 Dec 2018)

Thanks for the input guys! I had a sneaky feeling that this was causing the algae to take over!! As a quick fix I have just killed the blue light in the evening, later this week I will adjust the timing of everything so I can still get a few hours viewing in the evening by having everything start later in the morning. Since making some changes to ferts, co2 levels, maintenance and getting a clean up crew I have noticed a significant reduction in algae, so hopefully this final adjustment will hit the nail on the head  The irony is I got these lights and controller (at a higher price!) precisely because I could set it up for evening viewing haha


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