# Blue-green algae is back



## jaybird002 (May 12, 2006)

I thought I got rid of the blue-green algae a couple of years ago when I put ivy type cuttings in the tank and let them take root and grow out of the water. Now the yucky algae is back. It is smeared all over the floating hornwort, but strangely not on the gravel or sides of the tank. It seems to trap air bubbles and looks awful. (Easy to remove, but it's futile. It is blue-green algae, right?)

I tried removing the affected portions of the hornwort but that didn't help. The problem got much worse when I took out a few jungle vals that had taken over the 29-gallon tank, covering about a third with their folded up leaves. I also took out the duckweed, which I wish I hadn't.

So how do I get rid of the blue-green algae? What does it need that I can take away? Should I replace the affected hornwort with a whole new batch? Add activated carbon to the filter? Replace my 55-w compact fluorescent with a regular 40-w flourescent? Cut down on hours of light per day? Add duckweek? Change the water? Pout and saulk?

Thanks for any help you can provide.


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## aquabillpers (Apr 13, 2006)

Hi, Jaybird002,

The easiest way to get rid of BGA is to dose 200 mgm of erythromycin per 10 gallons for 3 to 5 days. Before starting, remove all of the BGA that you can, and each day remove the newly dead. At the end of the treatment, you might do a partial water change, but if you were careful to remove most of the dead stuff that would not be necessary.

To keep it away, have a lot of healthy plants and keep the tank clean.

Easy, eh?  

Bill


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## jaybird002 (May 12, 2006)

Thank you for the suggestion on erythromycin. I may try that, although I have heard that BGA can become resistent to this drug. My inclination is first to try other things to subdue the algae with stronger plant growth. How can I make conditions (light, water conditions, etc.) more favorable to plants and less favorable to algae? Since most of the BGA is on the floating hornwort, I assume I should remove that and replace it with a fresh batch of hornwort. Anything else I can do?

Thanks.


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## aquabillpers (Apr 13, 2006)

jaybird002 said:


> Thank you for the suggestion on erythromycin. I may try that, although I have heard that BGA can become resistent to this drug. My inclination is first to try other things to subdue the algae with stronger plant growth. How can I make conditions (light, water conditions, etc.) more favorable to plants and less favorable to algae? Since most of the BGA is on the floating hornwort, I assume I should remove that and replace it with a fresh batch of hornwort. Anything else I can do?
> 
> Thanks.


Jaybird,

Here are some links about BGA treating. You will note some conflicting advice. 

http://aquamaniacs.net/forum/cms_view_article.php?aid=137

http://www.aquariacentral.com/forums/showthread.php?t=113224

http://www.barrreport.com/algae-control/993-blackout-failed-bga.html

(I found these links by googling - bga aquarium treatment - without the dashes.)

I think the best approach would be first to get rid of the BGA and then correct the conditions that are limiting plant growth. Be sure that you have a lot of fast growing plants.

I'd remove as much of the BGA from the hornwort as possible and then leave it in for the treatment, to see what happens. Alternatively, perhaps you could find a piece of it that wasn't infected and keep only that.

I have heard speculation that some BGA species can become resistant to erythromycin but it has been just that. I've never read of a plant grower encountering it.

Good luck!

Bill


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## Sushi Monster (Jun 10, 2007)

The plants that you removed were sucking up the nutrients. After removing them the algae had much more to feed off of. 
I would start by putting more plants in there that frow quickly. Do a 50% water change AND not letting light in your tank for 2 days.  
Good luck!


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## JJJohnson (Mar 29, 2007)

Blue-green algae/cyanobacteria/"cyanoslime" is the worst, and once you have it, it's very hard to get rid of. Erythromycin will definitely kill it, but you can't keep dosing the tank with antibiotics forever, and when you stop, chances are the BGA will come creeping back if you don't make any other changes.

The thing that worked best for me was cutting back on the light intensity and especially duration. Lots of water changes and increased circulation in the tank can help too. Good luck!


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## jaybird002 (May 12, 2006)

Thanks folks,

I've done several of the things that you suggested. I switched from a 55w compact fluorescent to a 40w regular fluorescent for my 29 gallon tank. I changed about a third of the water, put in new activated carbon, and turned up the filter circulation. Most the the BGA was on the hornwort, so I removed most of it and replaced it with a fresh batch of hornwort. I also kept the "heads" of the old plants, which were the fastest growing pieces, and scraped as much of the algae off them as possible. Also I added a big water sprite, which is sprouting baby plants. I will let them float to the surface and grow, extending their roots and sucking up the nutrients. There are also a few specks of duckweed, which I hope will multiply and starve out the BGA. I am also reducing the amount I feed the fish. Is this OK, as long as the plants don't start looking pale form lack of nutrients?

Wish me luck.


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