# Photoperiod reduction and algae



## MatPat (Mar 22, 2004)

Since my daughter arrived in late January, I have found I don't have as much time as I used to for tank maintenance. Prior to her arrival or shortly thereafter, I began to have some issues with green dust and some minor green spot algae. Not having the time to do proper maintenance on my tanks I decided to reduce the photoperiod on all of my tanks. I think Chiahead may have suggested this in a thread on green dust algae.

As a result of reducing my photoperiod from 10 hours to 8 hours I have found nearly all of my algae issues have been either greatly reduced or have completely disappeared. Nothing else in the tanks has changed except for the fact that I do sometimes forget to add ferts when I should. With the reduced photoperiod I get slower plant growth, less algae, and reduced maintenance which is a big plus for me right now 

Considering today's higher output lighting, should the "average" hobbyist reduce their photoperiod in order to control algae?

Will reducing the photoperiod work or did I just get lucky?


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## Zapins (Jul 28, 2004)

I did the exact same thing for GDA. Had 220wpg above a 55, and reduced it to 110w. Green dust greatly decreased in # Others should try this method out for GDA and see if it is a reliable solution.


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## John N. (Dec 11, 2005)

It's definately worked for me. Everytime I have an algae problem I back off the lighting by an hour or two. It should be noted with a reduce lighting period, slightly less ferts need to be dosed too and will expediate the decline of algae.

-John N.


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## upikabu (Sep 2, 2005)

Interesting. I will try this on my algae-infested tank. I assume you would also adjust CO2 "on" period accordingly, or does it not matter?


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## John N. (Dec 11, 2005)

I personally think additional CO2 helps to decrease it by helping plants grow more efficiently. If anything, we know that extra CO2 doesn't cause algae. But if you are reducing everything else, CO2 can also be reduced too if you want. 

-John N.


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## hoppycalif (Apr 7, 2005)

My gut instinct tells me that if I reduce my lighting period from 10 to 8 hours, the reduction in fertilizer used will be small - 20% or so. So, I think I will try this too, but not reduce fertilizer or CO2. I am a recovering GDA "addict" right now, using the "let it go thru the life cycle" method, but the two weeks when I couldn't see a thing in there has left me with a bit of blue green algae and a few spots of BBA too, which have me raising my ppm of CO2 and my nitrates. The lighting reduction makes some sense too.


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## Bert H (Mar 2, 2004)

IMO, lighting intensity and duration are perhaps,the two most important factors in algae control, and certainly the easiest to control. So many people seem to want a high light, fast growth type tank. In tanks over 30gal, you can probably grow most anything with 2.5wpg, assuming you have good reflectors. Some of the red highlights may not be there, but the algae won't either. We all make our choices...


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## hoppycalif (Apr 7, 2005)

My feeling was that I wanted to try various types of tanks for growing plants, just to see what was best for me. I tried 1.75 watts per gallon for awhile, but got frustrated by knowing what plants I couldn't consider trying. Now, I am at what is clearly high light - 3.8 watts per gallon - and I love the appearance of the plants, but the unending battle with algae may persuade me to try lower light. If we don't try various schemes we never know if a different way will suit us best. Everyone warns us that high light comes with algae problems, but until we try various ways to work around that we will always wonder if we should have gone that way.


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## Fiki (Apr 16, 2006)

Have to say I agree 100% with Hoppycalif. If we don't try, how can we know? Less light in AQ automatically means less ferts or vice versa (level of CO2 is a less important). There should be some precise relation...

Regards
Fiki


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## MatPat (Mar 22, 2004)

Fiki said:


> Less light in AQ automatically means less ferts or vice versa (level of CO2 is a less important). There should be some precise relation...
> 
> 
> > I don't think we need to be that precise in our ferts as long as we are giving the plants enough and doing weekly water changes.
> ...


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## Avalon (Mar 7, 2005)

Good topic here. Now the question may be "how low can you go?

I had a 100g tank once with extremely low light (1.6w NO, no reflectors) and some window light. It sustained lots of plants for 2 years, and some even grew a little, and it had little to no algae. You really had to look for it. Here's the kicker: NO3 was always over 40ppm and PO4 was always over 5 ppm (big fish). I only added some traces and K at wc. I wonder if you worked things out with the light, you could just add macros on a weekly or twice weekly basis and only do wc's once a month? The wc's on the aforementioned 100g did nothing for the plants; they were only to keep the nitrates under 80ppm.  

My other question is how do some people keep these extremely high light tanks with no algae? Or do they have it and just do a lot of scrubbing?


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## 247Plants (Mar 23, 2006)

Im running about 3wpg NO on my 65gal without CO2 but with excel and I dose micros as usual and macros about once every two weeks in a heavily planted tank and when I first started to keep a planted tank I was running about a 12-14 hour photoperiod and had a massive bout with diatom algae, as soon as I cut the photoperiod by about 2 hours EVERYTHING cleared up and rarely do I ever see any algae.....I only have to clean the glass because of the very light dusting of detritus every WC.


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