# Green Dust Algae



## Hookahh (Aug 24, 2010)

So i have "Green Dust Algae" on my aquarium's glass. I clean it off but it wont go away and appears within days. What do i do? How should i get rid of it? I have one algae eater but...lol he is lazy.

Dry IE Dosing
DIY CO2 
1xCFL 15w
1xT8 15W


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## Darkblade48 (Jan 4, 2008)

Tom Barr has an interesting method of removing GDA. Essentially, you leave the GDA alone for several (3-4) weeks and it will create a mat. Once this occurs, it will simply slough off, and should not come back.


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## MarkMc (Apr 27, 2007)

Or you can tweak the CO2/ Light thing and it will go away. You don't say what size the tank is so I'm assuming that it is small. Ten gallons? Maybe you don't have enough CO2 for the amount of light?


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## Hookahh (Aug 24, 2010)

Oh yeah sorry its a 10G, i have 2 coke bottles and a little Hagen water pump so diffusion is good. Do you suggest i keep only 1 of the lights on? I just feel like the nutrients would go to waste


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## neilshieh (Sep 6, 2010)

water params? GDA sometimes occurs from nitrate swings.


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## MarkMc (Apr 27, 2007)

Hookahh said:


> Oh yeah sorry its a 10G, i have 2 coke bottles and a little Hagen water pump so diffusion is good. Do you suggest i keep only 1 of the lights on? I just feel like the nutrients would go to waste


Yes that would help. Reducing light lowers demand for CO2 thereby _increasing_ the amount available! You can adjust the amount of ferts added accordingly. Plants and animals are carbon based so think of CO2 as the most important food item that plants need.


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## timwag2001 (Jul 3, 2009)

try tom barrs method. worked great for me. if you keep scraping it it wont go through its whole life cycle. let it sit and it builds up and lives its life out. you will pretty much see it falling off of the glass. then scrape it and do a huge water change (80%). that should solve the problem. if it doesnt work the first time you might have to do it one more time


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## MarkMc (Apr 27, 2007)

timwag2001 said:


> try tom barrs method. worked great for me. if you keep scraping it it wont go through its whole life cycle. let it sit and it builds up and lives its life out. you will pretty much see it falling off of the glass. then scrape it and do a huge water change (80%). that should solve the problem. if it doesnt work the first time you might have to do it one more time


That's great but shouldn't the OP fix the reason the algae is there? 30 watts of t8 and cfl sitting right on top of a 10 gallon tank is a good amount of light over a shallow tank wouldn't you say?


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## timwag2001 (Jul 3, 2009)

yes high light will cause it but i also got it in my low light tanks with co2. 
in the tank that i had the most issues with was my 55gal. i had 4 54 watt t5ho bulbs over it, thats a lot of freaking light! after the method that i followed up above it went away for good.


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## plantbrain (Dec 15, 2003)

neilshieh said:


> water params? GDA sometimes occurs from nitrate swings.


I have found no support for NO3 swings.
Also, swings is non descriptive.
In other words, it's not helpful without real ppm included, say going from "4ppm to say 30ppm".
Or keeping a range "between 10-20ppm"

That's useful, "swings" does not tell us much, we learn little.

I've gone farther, but there's little point. Also, sediment ferts sources are not included for N.
Since my ADA As is old, it's been tested and has little available N.

So while the water column might have a lack or a swing of N, the sediment very well may not.
Without measuring it, hard to say.

Plenty of folks have tried in vain to do lots of water changes and many have not dosed after to see if any effect occurs....this is met by failure as well.
Adding NO3 also did not seem to have much effect.

Since I have 5-6 tanks and only the ones with the CO2 has issues, I find it difficult to support NO3 swings, since all tanks got the same KNO3 dosing and only one tank , the one with poor CO2, ever had or could sustain GDA.
Repeated inoculations prove fruitless to the other tanks with good CO2. GDA is rather harmless to plants, so such test have little harmful effects on plants. Same for GW.

I can rule things out, but it is tougher to assign blame to CO2.
Still, I cannot falsify CO2 at this time.

Since I have several tanks: I can measure the light in relative terms of PAR, measure CO2 with high accuracy, Dosing is rather a simple affair, I can look at the whole picture.
I know the sediment for the most part and have tested the ADA, the Flourite and plain sand are fairly easy to look up as well. So things are fairly independent between the tank except the CO2.
Adjusting it.......and the GDA has never come back.

I also tried something else, I took the CO2 off.
This knock it back.

I think some have tried adding peat, that seemed to work as well.
But at the root, the CO2 seems to be the biggest factor.
Higher light seems to exacerbate all algae issues.
And more light => more CO2 demand which would also support observations also.











Regards, 
Tom Barr


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## captain_bu (Oct 20, 2007)

neilshieh said:


> water params? GDA sometimes occurs from nitrate swings.


I am relatively sure that you are confusing BGA (cyanobacteria) with GDA. BGA can be related to low nitrates.


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## !shadow! (Jan 25, 2010)

captain_bu said:


> I am relatively sure that you are confusing BGA (cyanobacteria) with GDA. BGA can be related to low nitrates.



l think so too. l've had both and well it's widely known that bga is a lack of nitrates as l soon found out after l dozed some kno3. gda is rather a bit of a mystery as to what causes it but l agree on the method on leaving it alone and let it live out it's life cycle which is about a couple of weeks(about 3-4 for me) before its safe to scrub it off.


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## Dave B (Jun 27, 2007)

I figured it'd be better to bump this than start my own thread...

Today I finally gave in and cleaned the glass of my plant-free African tank. (Took forever!) It had GDA but 6 weeks of leaving it alone didn't do anything.

Did I mis-diagnose? It seemed to be pretty obviously GDA. Nothing like the spot or any other type that I know of. Very hard to scrub off, turned the water green, etc...

It started in this tank when I temporarily had some very powerful lights (from an old planted tank) over the tank for about 2-3 weeks. It nearly tripled the usual output, and even though I went back to the usual amount afterward, the GDA remains.

Today's scrubbing came during a WC that was as close to 100% as possible (once I reached about 20% remaining I had one python filling and one draining for quite a while til I finished scrubbing), so I suppose maybe there's a chance I got rid of a lot of it... but I doubt it. There's still plenty living on the rocks and the back glass behind rocks. I'm sure it'll be back.

So... now what?


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## timwag2001 (Jul 3, 2009)

if its on the rocks its not gda. and gda is very easy to take off. you must have gsa


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## Dave B (Jun 27, 2007)

timwag2001 said:


> if its on the rocks its not gda. and gda is very easy to take off. you must have gsa


It's definitely as tough to remove as GSA. But IME GSA has always been those larger green blotches (a few mm diameter). This is much more like... well, dust. Which is what brought me here.

And it comes back right away too. Perhaps I gave birth to a resistant hybrid mega strain of killer green algae. Would fall right in line with my recent luck in my tanks...


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## timwag2001 (Jul 3, 2009)

i've noticed that there might be two different kinds too. the one thats much larger which in my experience goes away when increase phosphates and the smaller one that seems to be purely from too much light.


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## Sharkfood (May 2, 2010)

I tend to agree with the phosphate method. I had a GSA problem in my main tank, and upping the phosphate coupled with the occasional scraping before water changes has knocked it back to almost nothing. I can't say that there is a direct correlation with P dosing, but it did work for me. Currently, my grow out tank is starting to show some GDA issues which I haven't sorted out yet. (This tank has a 12hr photoperiod, which is not going to change, so I have some thinking/experimenting to do.)

Let me stress that this is a general trend that occured over several months, and P dosing didn't eliminate GDA immediately. Also, the tank isn't totally free of GDA. If I were to go a couple months without cleaning the glass you would be able to see the haze. There are some spots in the back also where I can't clean that still have the old GSA that I never removed around driftwood, etc (it didn't die off with added P). Some spots did die however, leaving what seems like a calcium or silica deposit behind.


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