# Green dot algae



## cradleoffilthfan (Jan 19, 2009)

add a UV sterilizer. The green dot algae isn't too bad a deal, I would get one of those magnet cleaners and just wipe the glass down daily to make sure it doesn't get a chance to gain a foothold. If you added a UV sterilizer, you wouldn't have to worry about it anyway. It might be worth looking at.


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## Denis Onii (Jul 2, 2010)

Low PO4 seems to be a factor with GSA. The likely scenario is that the amount of PO4 you are dosing isn't enough for your lighting period. Either increase ferts or lower lighting.

Personally I would lower lighting to 6 hours for couple of weeks. If that eliminates the GSA then slowly increase lighting along with ferts until you get back to 10 hours.


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## msawdey (Apr 6, 2009)

+1 on the UV... i still get it on my 55 gallon, but for the most part its kept under control, just use a mag to clean it off when you do a water change


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## 150EH (Dec 6, 2004)

Or you might split the difference and reduce the photo period to 8 hrs. and you should be adding one third phosphates to your ferts so if you were adding 10 teaspoons of KNO3 you would then mix in 3.33 teaspoons of KH2PO4 to you solution or how ever you might do it. I used to use a UV sterilizer but they are expensive and don't last a long time so I find it better to just find the problem and make the corrections and most of the time if you just make the proper adjustment and watch for a couple of weeks you'll get results.

My algae is under control to the point that I only have a very slight amount of dust that is not visible unless you look hard and the MagFloat takes it right off.


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## Denis Onii (Jul 2, 2010)

150EH said:


> My algae is under control to the point that I only have a very slight amount of dust that is not visible unless you look hard and the MagFloat takes it right off.


GDA is related to ammonium. Increase efficiency of your filter or reduce feeding. Wiping it off isn't very effective - GDA is flagellated, all that survive scraping will return to the glass at night.


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## Mr. Fish (Apr 24, 2012)

Some of the info given here is incorrect.

GSA is generally caused by low phosphate levels. Also Low CO2 and poor water flow. Too long of a lighting period doesn't help either.

Firstly I would make sure your co2 levels is reading 30ppm and make sure your water flow is not restricted. If everything is in check I would dose a bit more of phosphate and wipe it down or add a cleanup crew to keep in check.


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## 150EH (Dec 6, 2004)

Denis Onii said:


> GDA is related to ammonium. Increase efficiency of your filter or reduce feeding. Wiping it off isn't very effective - GDA is flagellated, all that survive scraping will return to the glass at night.


What?


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## Mr. Fish (Apr 24, 2012)

150EH said:


> What?


+1 LMAO :biggrin:


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## Denis Onii (Jul 2, 2010)

150EH said:


> What?


Chlamydomonas is probably the most studied algae on planet. More is known about it than any other. It's used as a model because it's easy to to cultivate and has many aspects to it's physiology.

http://www.amazon.co.uk/s/ref=nb_sb_noss?url=search-alias=aps&field-keywords=chlamydomonas&x=0&y=0

GDA goes through it's daily cell cycle. Each adult cell will divide internally up to 3 times a day, producing 2, 4, or 8 zoospores. They break out and grow into adult cells. This is the algae's method of asexual reproduction and it repeats continously *under favourable conditions*. 

Eventually the number of cells will increase and the glass will go green. During the (subjective) night, the cells produce a substance that is responsible for them sticking to the glass. Flow in the tank will push more cells onto/passed certain spots and they will build up.

http://www.plantphysiol.org/content/63/6/1175.full.pdf+html

How long it takes before you see this buildup depends on level of ammonium, intensity of light, presence of calcium, temperature (apparently 33 celsius will halt the cell cycle completely!), possibly flow and as always, other stuff! You can slow this process down by reducing light intensity and reducing ammonium but you can also halt it.

To do this you can provoke the adult cell it into it's sexual cycle. There it will eventually end up as spores, no longer dividing asexually and effectively frozen in time. To achieve this, you have to subject it to unfavourable conditions which is known to include removal of ammonium (but might include other sources of N also).

http://pcp.oxfordjournals.org/content/33/7/909.abstract
(and others)

Now, the adult cell no longer divides into zoospores, but instead divides into gametes. These burst out, swim around and pair with each other, grow into a zygote and turn into a zygospore. You can tell when this has happened because the GDA will go a reddish colour due to oils and starch being stored in the spore.

This is a know method to get rid of GDA. Leave it for 3 weeks, let it go red, clean it out then it won't come back. This doesn't always work, possibly because it only works when GDA is in it's sexual cycle, ie in the absence of ammonium. If you have ammonium in your tank, you will be stuck in the perpetual cell cycle of asexual division.

http://www.youtube.com/watch?v=Foh7osrNNZU

http://academic.kellogg.cc.mi.us/herbrandsonc/bio111/animations/0117.swf

http://sjbscience.weebly.com/uploads/2/7/5/3/2753626/chlamydomonas_v2.swf

It also uses phototaxis to swim toward the light in the day (to grow) and chemotaxis to swim toward a source of ammonium at night (to reproduce). Once it attaches to the glass it will divide. It does this at night to avoid UV damage during DNA replication - a feature that developed billions of years ago when the planet had little or no ozone and UV was far more dangerous.


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## HD Blazingwolf (May 12, 2011)

Ur leaving out a major factor. Plants fight a chemical war with algae much as ur body does to parasites and infections. Algae is an infection to plants therefor they release chemicals that inhibit growth of algae. Ina closed system it protects the tank. In open moving bodies of water. It just protects the individual plant. Unhealthy plants are unable to protect themselves if they are having trouble growing. This is why healthy plants usually mean a clean tank


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## plantbrain (Dec 15, 2003)

Denis Onii said:


> GDA is related to ammonium. Increase efficiency of your filter or reduce feeding. Wiping it off isn't very effective - GDA is flagellated, all that survive scraping will return to the glass at night.


No, the 1st time I ever saw GDA the owner had a nice wet/dry filter..........

There was no NH4.

I've dosed NH4 and have large fish populations, never was bale to keep a culture for long except for one small tank.

Anyway, the OP posted about GSA, not GDA.
GSA is fairly well understood,: higher PO4 and higher CO2(not just one but both).

GDA is NOT _Chlamydomonas_, it is actually _Akineoscedesmus_. If you take a sample, look under a scope, you will see this Genus. I have not found the species, I do not think it matters so much for us and it's tougher to ID. 
Sewingalot has a few pics of it and her method usign EM antibiotics worked for some folks, but not others. My method of letting it be and run the course and then cleaning after 20-30 days seems to have the highest success rate, but...there are plenty of folks that still had issues.
Hard to say what causes it, the observations are pretty wide, and I am not able to induce and maintain any cultures, without being able to do that, there's little one can do to test in situ on a planted tank.

So we cannot say much about cause nor cures. Folks can try a few of the methods to cure their own issues, I really do not fuss with that, I stick to good plant growth and good care of the plants, this works better than any algae trickery in the last 20+ years I've kept planted tanks.


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## Denis Onii (Jul 2, 2010)

plantbrain said:


> GDA is NOT _Chlamydomonas_, it is actually _Akineoscedesmus_. If you take a sample, look under a scope, you will see this Genus. I have not found the species, I do not think it matters so much for us and it's tougher to ID.


Tom, it has been identified under a scope as Chlamydomonas, thats not to say it's right. A quick search through multiple search engines and algaebase suggest that there is no such thing as Akineoscedesmus, do you have any links?


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## HD Blazingwolf (May 12, 2011)

Denis Onii said:


> Tom, it has been identified under a scope as Chlamydomonas, thats not to say it's right. A quick search through multiple search engines and algaebase suggest that there is no such thing as Akineoscedesmus, do you have any links?


 
Unfortunately. algae is like a well known bacteria. in layman's terms. you have cold bactera A. well it also has 3,479,587,912 different strains

i may be wrong but the only resulting search google may provide for that algae is because its a subspecies not completely categorized and explained.
i know nothing of this just my assumption as to why googl wouldn't return a search on a specific algae


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## Denis Onii (Jul 2, 2010)

I am usually inclined to believe Tom, but he is talking about a genus not a species or strain so it's difficult to believe Akineoscedesmus could exist yet have absolutely no mention on the internet across multiple search engines and algae resources. Maybe he spelt it wrong. Alga does get moved about and renamed a fair bit, perhaps it got recategorized as one of the 500 or so Chlamydomonas species. It's also hard to identify some algae using a microscope alone. If you scrape GDA off the glass you won't see a flagella because this gets absorbed so it appears as a green cell, like alot of other algae.

I hope he can provide some evidence for it's existance.


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## Rony11 (Jan 21, 2012)

I did everything that was adviced in this thread it took some time but now I am able to control the green spot algae. This is what I did..

1.Water changes 50% every weekend.
2.Reduced the light to 0.8 w/l - reduced light hours to 7 hours on a timer.
3.Cleaned the affected glass with miracle sponge and pruned the plant leaves affected with green spot algae.
4.I've improved my tank water circulation by cleaning the external filter, started cleaning the ceramic rings and changing the perlon once in two months in my external filter. I clean the spray bar once a week, prune my fast growing plants on a weekly basis, siphoning the debris which accumulates at corners on a weekly basis, cleaning the glass which had green spot algae once a week.
5. I reduced my fertilizing routine from everyday to twice a week.
6. Abt. CO2 I dont use the atomizer anymore. I added a good ceramic diffuser and clean the ceramic disc on weekly basis. I have 2 bubbles per second. 

I still have green spot algae but it is not as irritating (spreading like crazy) as it was in the past. I can see the difference and I must say thanks to everyone who gave me gr8 advice.


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## 58417 (Dec 18, 2012)

*GDA = Chlamydomonas and/or Ankistrodesmus*



Denis Onii said:


> Tom, it has been identified under a scope as Chlamydomonas, thats not to say it's right. A quick search through multiple search engines and algaebase suggest that there is no such thing as Akineoscedesmus, do you have any links?


I think it should be not _Akineoscedesmus_, but *Ankistrodesmus* (which belongs to the same class as *Chlamydomonas* => Chlorophyta > Chlorophyceae).

Still I know of some professors who identified this "green dust algae" on the glass of freshwater aquarium as "Chlamydomonas" also. I'm not saying that Tom Barr did not have Ankistrodesmus under his microscope, but our GDA could be Chlamydomonas as well as Ankistrodesmus.


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## gpeach (Sep 9, 2014)

*Getting rid of GD*

We have a planted tank with GD algae. Found a reference on the fish channel - they said to scrape with a razor blade because algae eaters have a hard time eating it. We bought a paint scraper and it scrapes off the glass easily, and now its under control.


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## FatherLandDescendant (Jul 24, 2014)

gpeach said:


> We have a planted tank with GD algae. Found a reference on the fish channel - they said to scrape with a razor blade because algae eaters have a hard time eating it. We bought a paint scraper and it scrapes off the glass easily, and now its under control.


Be careful not to scratch your tank


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## 58417 (Dec 18, 2012)

*GDA = Chloroccocum*

Here are some macro- as well as micro- pictures of the green dust algae on my tank's glass:

Macro pictures:




































Micro pictures:

400x:









1000x:









1000x:









400x:


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