Increasing photoperiod / light intensity to combat cyanobacteria? - The Planted Tank Forum
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post #1 of 5 (permalink) Old 03-31-2013, 03:34 PM Thread Starter
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Increasing photoperiod / light intensity to combat cyanobacteria?

So we all know that cyanobacteria, or blue green algae, isn't really algae. So we can theorize that it doesn't have the same relationship with light that algae does.

A couple of years ago when I first got into planted tanks I started out with a dirted low tech setup. Eventually, BGA started popping up on the sand. After stirring it up or trying to siphon it out, it would reappear overnight. I read and tried many different solutions until I came across someone suggesting to actually increase the intensity and photoperiod of my lighting.

Sure enough, (at least in my case) there seemed to be a direct inverse correlation between the amount of light my tank received and the amount of BGA.

I added another fixture and left my lights on overnight and in the morning the BGA was significantly reduced. I put my lights back on their normal schedule, and the BGA came back the next day. So then I left my lights on for something like 72 hours straight, long past when the last signs of the BGA had disappeared and it never came back.

Fast forward to today. I'm trying my first high tech tank and it's not going great. I planted my bunches of Dwarf Hairgrass and things looked great for about 3 weeks. Then in one weeks span, BGA invaded and the substrate and DHG were a mess. For about a week and a half I tried the usual methods of removing the BGA. Checking nitrates, phosphates, manual removal, etc.

So last night I decided to leave my lights on overnight. As of typing this, they have been on for about 24 hours, and the BGA is once again, SIGNIFICANTLY reduced. Usually it would spring back to cover about 1/2 of the substrate overnight after siphoning it out. Right now, however, it's confined to one spot on the substrate about the size of a tennis ball.

Has anyone else had an experience like this or does anyone have any thoughts about what might be going on here?
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post #2 of 5 (permalink) Old 03-31-2013, 05:57 PM
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In my 29g i had little spots of gba pop up. started reading and one method people suggested that you could possibly have low nitrate. i upped my dosage of kno3 and i am bga free to this day. but this is just from my personal experience.
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post #3 of 5 (permalink) Old 03-31-2013, 08:56 PM
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Increasing KNO3 dosing always helps me when I get BGA, but I haven't tried leaving the lights on much longer. I don't see a reason for the extra light helping, though, so I doubt that I will ever try it.

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post #4 of 5 (permalink) Old 03-31-2013, 10:06 PM
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Increasing photoperiod / light intensity to combat cyanobacteria?

From my experience it was mostly due to low flow. I had the same problem as you did where I would take it out and then next day it would be right back where it was. Added a powerhead to get better flow around the bottom of my tank and it never came back
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post #5 of 5 (permalink) Old 03-31-2013, 10:43 PM
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im not sure about leaving lights on longer, but i have noticed that adding UV to the tank seems to dramatically reduce BGA. i switched regular CFL bulbs for the 10 UVB reptile bulbs on one tank and the cyano quickly vanished. since then, i try to add a source of UV to all my tanks. i dont turn the lights off of any of my tanks and only one gets BGA regularly. that particular tank is full of algae and tannins, and its purpose is to grow fry out, not look pretty. it does its job quite well, despite looking like crap.
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