# GDA - chances it will come back?



## evercl92 (Aug 14, 2006)

Specs:

120gal 4x2x2 tank
Eheim 2028 canister
Pressurized CO2
Two sets of 2x54wt T5 HO lifeglo2 bulbs
1st set of lights are on for 10.5 hrs
2nd set comes on then off while 1st set is one, for 8hr period

Here is what my tank looked like earlier today:




Then, I cleaned the glass pretty good, then did a 75% WC about a hour later (hoping the filter would catch some of the algae). Then washed out my filter, put the tank back together.

Then it looked like this:


I just realized that the photoperiod was that long today. I've since adjusted it to 8.5 hrs and 6.5 hrs for the 1st and 2nd sets. 
Typically, I test and dose ferts 2x week... typically.
Recently, I've been lacking, so I think that's an issue as well.

I usually keep dose:

KNO3 to get nitrate to 25-30
KH2PO4 to get phos to 2
CSM+B 1/2tsp 2x/wk
K2SO4 1.5 tsp 2x/wk

Any reason to break out my UV sterilizer and run it for a couple days?
What is the likelihood that the GDA is going to return?
In the 2nd pic, are those diatoms? (unlikely...?? since the tank has been up and running over a year)


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## hoppycalif (Apr 7, 2005)

GDA is a strange algae. My experience is that once you get it you generally have to go thru several attempts to get rid of it before it finally doesn't come back.


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## evercl92 (Aug 14, 2006)

and what's my best option for attempting removal (even though it may take several tries?)


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## hoppycalif (Apr 7, 2005)

From what I read there are two basic approaches for fighting GDA. One is to leave it alone for two weeks or so to allow it to grow through a complete life cycle, then when it starts to drop off by itself, remove it. The other is the brute force method. Just clean the glass, the substrate, and any hardscape thoroughly, then replace 70% or so of the water, followed by another 70% or so replacement. Repeat this every day for several days, keeping the tank and water as clean as possible, with good nutrient supply and good CO2 all that time. If you do the first method, followed by the second method, you have the best chance for success. I have done the first method about three times, and eventually the GDA didn't return. I did a partial second method after one first method, and it was better than just the first method. A problem I kept running into was that a green fuzz, which may have also been GDA would attack all plants at the same time, and that would require removing those plants if doing the second method.


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## mikenas102 (Feb 8, 2006)

I used to have a GDA problem in my 30 gal. I tried the first method several times and never had success with it. What finally got me totally GDA free was similar to hoppy's second method. I cleaned the glass AT LEAST every other day. Everyday is preferable. After cleaning the glass do about a 50% water change. After the water change I added a clarifier. I used Seachem's Clarity. I know they aren't the greatest things to use but it works in this case. By adding it right after the water change it binds to the remaining floating spores of GDA that weren't removed by the water change. The next day after adding the clarifier you have to clean your filter and rinse the sponges in the filter very well. Do this method every day or every other day and in about a week and a half you should be GDA free. Now to keep it from happening again I found it is extremely important to reduce your lighting time. In my opinion GDA is about 90% light duration related. I reduced from 9 hours to 7 1/2 hours and have never had a problem again. I was so frustrated with GDA for some time that it nearly caused me to quit the hobby. If your willing to put the work in that I mentioned for a week or two you'll be happy you did.


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## MatPat (Mar 22, 2004)

I've used a similar approach without the water changes and substituting a diatom filter (Magnum 350 with micron Cartridge). I clean the glass at least daily (usually twice a day) and just leave the filter running. In 7-10 days the Green Dust has usually subsided and I replace the now green micron cartridge with a clean one. Seem to work in my case. It would really be nice to figure out the cause of this stuff though.


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## mikenas102 (Feb 8, 2006)

I wish we could point to 1 thing and say "that's it!" but nobody can do that with this stuff yet. I firmly believe though that it is heavily dependant on light intensity and duration.


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## helgymatt (Sep 12, 2007)

My first attempt to "let the algae go" for 3 weeks was a failure. I may try another attempt, but I want to SEE my plants and fish for a while, rather than algae for nearly a month (thats the problem I have with this method of control).


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## evercl92 (Aug 14, 2006)

I'm off tomorrow. I'll have to post an updated pic.


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