# My GDA battle



## apistaeasy (Jul 16, 2004)

*Winning the GDA battle*

So, my tank got GDA green dust algae really bad. All the literature suggested the only way to get rid of it was to wait it out and then wipe it off the glass...

I don't have the patience for the waiting method, and the algae was also on plants and wood that can't be wiped down easily.

This is what I did instead:

1. Disconnected the filtration system
1. Stirred up the tank as much as possible and removed as much algae from plants as possible, leaving the dust to go into the water column

3. While all the algae was in the water I removed 75% of the water. Every bucket full of water I dumped was very green.(algae getting dumped down the toilet, yeah!!!)

4. Next, I removed any decorations (including wood) and scrubbed them down with a sponge and brush, rinsing in regular tap water to remove all remaining spores.

5. On the plants I could not effectively rid the leaves of algae I did a bleach dip. BTW, Alternanthera reineckii does not do well with a bleach dip, but there isn't any algae on the plants anymore!

6. I then filled the tank up with water. I used straight RO, reconstituted with RO right.

7. Later, I connected a UV sterilizer.

8. Filtration came next. I use a Rena canister filter. The media I used were the sponges it came with, carbon, Purigen, and a microfiltration pad (batting for making quilts and such).

9. Lastly I used Clarity to clear up the water, and to help clump the algae particles together big enough so the microfilter could take it out. I then proceeded to clean the filter media about every 12 hours. Surprisingly, every time I cleaned the filter it was dirty - with dirty green water (algae spores I suppose). I used clarity about every 12 hours to keep the algae spores clumping together.

10. In addition, I also changed my photoperiod to 8 hours, and reduced my lighting from 4.7 wpg to 3.7 wpg.

I came home from work today to find the tank incredibly sparkly, and completely algae free. Just to make sure I cleaned the filter again, and the filter media rinsed more of a brown color instead of the previously green color.

I believe the most effective things were the 75% water change, the use of clarity, and the frequent filter media cleanings. I'm sure the sterilizer helped to kill the algae, and will help to prevent any future breakouts.

I hope this helps! post up your experiences with battling GDA too!


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## hoppycalif (Apr 7, 2005)

Very good cleaning practices do seem to be effective against GDA, so I'm not too surprised at your success. But, congratulations! Now, the real test will be to see if it comes back within two days. You can counter that by doing some serious tank wiping every day for three days, changing 75% of the water, and dosing 1.5X the Excel water change dose each time. I think this may end up being the preferred method against GDA.


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## apistaeasy (Jul 16, 2004)

oh yeah, I also dosed 1.5 or 2x Excel


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## apistaeasy (Jul 16, 2004)

It has been a couple of days now, and I haven't spotted any algae yet...although I have noticed a light film of something on the inside of the tank. I will try not to scrape it off the glass to see if I have really rid the tank of GDA.

If worse comes to worse, I'll do another 75% this weekend.


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## hoppycalif (Apr 7, 2005)

Don't ignore the slight haze!! Go wipe it off. Do that every day or two for awhile. If you ignore it now you will be back almost to square one.


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## apistaeasy (Jul 16, 2004)

thanks for the tip, tank is scrubbed. In addition, I'll probably rinse out the filter media later on tonight.


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## apistaeasy (Jul 16, 2004)

Just a quick update. I have used this method on several tanks since the original post with great results, even without the additional use of UV sterilization! 
For the other tanks I skipped the bleach dip as I have found it to be a little harsh on plants. 

I highly recommend this method.


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## Zapins (Jul 28, 2004)

I have battled GDA off and on over the last few years. At first I tried doing multiple water changes and UV/Diatom/scraping methods, but this never seemed to work, it always came back with a vengance and it took too long to clean each time.

I also hate waiting for a nice looking tank (especially since they are on display in my college admissions office), so I reduced the duration/intensity of the lighting and within about 4 days the GDA went brown and died off. I did a water change and sucked off the GDA which was easy to remove and it didnt grow back. 

I have tried reducing light intensity/duration on 3 seperate occasions and it has always worked which is good because I can't afford to have the tank green for 3 weeks with hundreds of potential students walking by lol...


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## hoppycalif (Apr 7, 2005)

Zapins said:


> I have battled GDA off and on over the last few years. At first I tried doing multiple water changes and UV/Diatom/scraping methods, but this never seemed to work, it always came back with a vengance and it took too long to clean each time.
> 
> I also hate waiting for a nice looking tank (especially since they are on display in my college admissions office), so I reduced the duration/intensity of the lighting and within about 4 days the GDA went brown and died off. I did a water change and sucked off the GDA which was easy to remove and it didnt grow back.
> 
> I have tried reducing light intensity/duration on 3 seperate occasions and it has always worked which is good because I can't afford to have the tank green for 3 weeks with hundreds of potential students walking by lol...


How much light did you end up with where it worked well? I still get relatively minor outbreaks of GDA, with 72 watts of AHS light over a 45 gallon tank. I suspect if I were more gung ho about doing routine weekly cleaning and maintenance I could defeat it.


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## rs79 (Dec 7, 2004)

It's caused by low phosphates. Just add PO4 and it'll go away.


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## hoppycalif (Apr 7, 2005)

rs79 said:


> It's caused by low phosphates. Just add PO4 and it'll go away.


Green spot algae is a result of low phosphates, but I haven't found that green dust algae is. Green dust algae wipes off easily, and green spot has to be scraped off. But, if you leave GDA on the glass for too long it gets harder to wipe off too. (If it doesn't just drop off by itself.) I suspect that more than one algae species is involved as GDA and possibly as GSA too, but we just call them GDA and GSA. My point being that the slightly different algae species may act differently.


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## Zapins (Jul 28, 2004)

I had 220 watts of PC Ah supply light on my 55 gal tank for 11 hrs, then i reduced it to 110 watts for 6 hrs initially then after it died off i raised it to 8 hours and it didn't return.

On my 125 gal tank there were 4x65 PC lights for 10 hours, then i reduced it to 2x65 w for 8 hours and it disappeared. 

It seems like the initial reduction in intensity does the most damage to the algae.


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## hoppycalif (Apr 7, 2005)

Zapins, that is very interesting. I know algae grows in response to light just as plants do. So, it makes sense that reducing the light could drop it below some kind of threshold where the algae would just stop growing. I now have 1.6 watts per gallon and still have algae, including GDA, so like most everything else involved in this hobby, more than one thing is the "key" to algae free tanks.


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## rs79 (Dec 7, 2004)

You sure they're not the same thing? Maybe I've never seen it then...


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## hoppycalif (Apr 7, 2005)

rs79 said:


> You sure they're not the same thing? Maybe I've never seen it then...


I am generally just embarrassed when I say I'm sure about something, so I won't say it now. But, I do think it very probable that GDA and GSA are two different algae, with very different characteristics and reacting to different "treatments". GDA quickly covers the whole glass of an aquarium that is hit with strong light, while GSA is just little green spots until it really gets out of hand. GDA wipes off easily and GSA won't wipe off at all, it has to be scraped off.


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