# GDA and Maracyn Experiment



## hoppycalif (Apr 7, 2005)

BertH's experiment with Maracyn, http://www.aquaticplantcentral.com/...ic-problems/50181-maracyn-gda-experiment.html, came along just as I started getting GDA in my experimental 10 gallon tank. The tank has an emersed grown "lawn" of glosso, and some rotalas for height. About 4 days after I added the water I noticed GDA starting. Here is what it looks like today:









The only way I can see an antibiotic, like Maracyn, affecting GDA is by considering GDA to be not quite an algae. GDA does start with zoospores, free swimming spores, which does make it different from the usual algae. Perhaps the Maracyn affects the algae only when it is still mostly zoospores. In any case, I will dump in a packet (10 gallon dosage) this afternoon, and report what effect it has.


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## hoppycalif (Apr 7, 2005)

After 24 hours, I can see nothing different about the GDA. Today I dosed the second day's dose. I plan to keep the daily dose going for two more days, then if nothing has changed, I will wipe down the glass, to get free swimming zoospores again, and continue dosing.


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## hoppycalif (Apr 7, 2005)

After 48 hours, and two doses of Maracyn I still can see no change in the GDA. This is discouraging enough that I am stopping this test. Tomorrow I will wipe down the glass and start dosing Maracyn again, to see if it will kill the zoospores.

The trap in waiting a long time to see if the Maracyn will finally kill the algae, is that it dies a natural death in as little as 2 weeks, possibly sooner. So, that isn't due to the Maracyn, but to the natural life cycle of the algae. However, when you wipe down the glass you liberate some zoospores which are free swimming in the tank. Those can restablish the colony, and usually do.


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## hoppycalif (Apr 7, 2005)

This morning most of the GDA is gone from the glass! It has been living out its life cycle, undisturbed by me. For the past 3 days or so the abundant "food" available has led to a big pond snail population boom, and they seem to be removing all of the algae now. If I have time tomorrow I will clean it off, maybe dose the Maracyn again and see if it comes back.


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## Erirku (Oct 5, 2004)

The thing I learned about antibiotics, is that it is for a bacterial infection and has nothing to do with a virus! At least it was a trial an error test. Glad to see that there are other possible methods of getting rid of algae. Good Luck.


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## hoppycalif (Apr 7, 2005)

Erirku said:


> The thing I learned about antibiotics, is that it is for a bacterial infection and has nothing to do with a virus! At least it was a trial an error test. Glad to see that there are other possible methods of getting rid of algae. Good Luck.


It is certainly true that antibiotics don't work for viruses. I'm not sure if antibiotics have any effect on simple life forms that are more complex than bacteria, but much less complex than fish - zoospores, for example. It appears to me that Maracyn doesn't affect GDA zoospores, but possibly it will when they are all free swimming.


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## hoppycalif (Apr 7, 2005)

Today I removed half of the water from the tank, carefully wiped and scraped the glass to get all of the GDA off, trying to keep the scrapings out of the water. Then I refilled the tank, added Prime and a dose of macro fertilizers, plus the water change dose of Excel. I added two envelopes of Maracyn, a double dose, to see if it will kill the zoospores left behind, and prevent the usual re-infestation of GDA. I haven't decided whether to repeat that dosage for another two days or not.


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## hoppycalif (Apr 7, 2005)

Three days later, the tank looks great, as far as GDA goes. I didn't add any more Maracyn because the day after the first dose the water was pretty cloudy. I don't see any GDA anywhere now.

My experience with GDA has been that it comes back when you do the "let it live out its cycle" method. The fact that for 3 days I see no sign of it returning could be a sign that Maracyn helped. But, no conclusion yet.


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## orion2001 (Mar 20, 2008)

Glad to see that you've managed to get rid of your GDA problem Hoppy. How are the glosso and rotala doing? Did you have any trouble with the glosso and the emersed-> submersed transition?

Oh and I have a question regarding the black sand. How in the world did you pour the water into the tank to fill it up without totally messing the sand up and potentially uprooting some of the plants? I've noticed that the sand is extremely easily shifted/compacted and forms indentations even when a few drops of water fall on it.


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## hoppycalif (Apr 7, 2005)

When I pour water into that 10 gallon tank I use a "simple tool" that comes from a TV dinner: http://www.aquaticplantcentral.com/forumapc/aquarium-equipment/45391-simple-tools.html
It works very well.

I have been paying more attention to the GDA in that tank than to the plants. The glosso looks just about the same as it did before I flooded it. The rotala is growing, but not particularly well. Before long I will try pruning, and report on that in my other thread.


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## orion2001 (Mar 20, 2008)

Haha, I love the TV dinner strainer! I'm going to go hunting in the supermarket this weekend. Thanks a lot and good luck with the pruning.


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## Bert H (Mar 2, 2004)

Hey Hoppy, I just found this thread. The more folks try out stuff, the more we can come to some form of conclusion of efficacy. For me, it appears the Maracyn knocked down the gda to about half of what it used to be after a weeks time, much more in line with what I'm used to seeing in my other 2 tanks. I used to see it starting about 2-3 days after water change, and it would be fairly thick by day 7. Now I see it around day 4-5 and it's not bad at day 7. 

It is possible that a low continuous dose of it might maintain it 'cleaner', but I don't want to go that route. The stuff ain't cheap.


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## hoppycalif (Apr 7, 2005)

My experience with GDA suggests that if you can fight it hard enough to actually get rid of it, it doesn't come back at all. My 45 gallon tank has had battles with it, but for months now I get only light GSA on the glass. It doesn't seem to matter how you get rid of GDA, and all methods are a pain in the backside, but once it is gone it stays gone. My hope is that Maracyn will help reduce the pain.


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## hoppycalif (Apr 7, 2005)

it has been about 10 days since I cleaned off the GDA and added Maracyn. I can find no sign of GDA now, or any other algae for that matter. I think it is possible that the Maracyn killed the free swimming zoospores that were released when I wiped down the glass, but I'm not at all certain. This type of attack on GDA would have to be repeated by several people all with the same good results before I would believe it works.

The method is:
Let the GDA grow without touching it for 2-3 weeks.
Wipe off the GDA that remains on the glass - much of it should have fallen off by then.
Change about 50% of the water in the tank.
Add a double dose of Maracyn for that size tank.

I hope someone else who is sick and tired of GDA will try this and report what happens.


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## dawntwister (Sep 29, 2007)

Excuse for my ignorance but what are GDA and Maracyn?


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## Gilles (Oct 12, 2007)

Green Dust Algae equals GDA
And Maracyn is a specially compounded broad-spectrum antibiotic which has been shown to be effective against a number of pathogenic bacteria associated with ornamental fish diseases. It was developed for complete but gradual dissolution in freshwater.


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## jmr201 (Jun 3, 2008)

GDA does not form zoospores. It is an algae called Chlamydomonas that is biflagellate. Meaning it has two rotors it uses for swimming. Once wiped from the glass they start swimming. I have witnessed this under a micrscope. So really antibiotics should have no real effect.


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## xspy (Mar 29, 2008)

jmr201 said:


> GDA does not form zoospores. It is an algae called Chlamydomonas that is biflagellate. Meaning it has two rotors it uses for swimming. Once wiped from the glass they start swimming. I have witnessed this under a micrscope. So really antibiotics should have no real effect.


awww.. just when I was about to do a victory dance.. I have GSA but it has never gotten out of control.


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