# Green Dust algae..solutions?



## aquasox (Sep 11, 2005)

I'm pretty sure I have green dust algae (GDA). It only sticks on glass and sometimes wood, but is not GSA as this algae forms more of a uniform film over the glass and is very easy to scrape off and "dust like"....you can basically take it off with your fingers. Problem is that is rebounds in 3-4 days.
Sorry do not have access to a camera right now. Also it does not seem to affect any of the plants.

I read that you are supposed to wait until it completes its life cycle before removing...I tried around 2.5 weeks, but to no avail. How long am I supposed to wait? Also some snails and ottocats are removing some of the algae...does this affect the waiting time?

Is there alternative solutions?

Tank specs: 2.6 W PC/normal T5 over 72 gallon, 60 ppm+ press CO2, EI ferts, 50 % H20 change weekly.


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## trenac (Jul 16, 2004)

When I started have green dust algae problems I cut back on nitrates and it disappeared in a few weeks. Until you get rid of it, just keep it scraped off the glass.


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## Jason Baliban (Feb 21, 2005)

trenac said:


> ......cut back on nitrates


Great advise. I always read people posting add more P, but i would rather add less then more.

jB


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## BryceM (Nov 6, 2005)

Same experience as Trena. I've had BAD green dust with nitrates in the 60 to 80 ppm range. At the time, my test kit showed about 10-20ppm. I got a Lamotte kit and did a few WC's. The green dust cleared up in a couple of weeks.

More recently I let it run its course and it took a month or so to go away. High CO2, good micros, and adequate phosphates help.


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## aquasox (Sep 11, 2005)

I'm dosing 3/4 teaspoons of Nitrate every second day except for Saturday.
Should I try for 1/4 tsps less or more? 

Phosphate is 1/4 tsp every second day.

So then I can scrape the glass off as usual?


I can test the water if NO3 and PO4 estimates help, but I don't think that they are to accurate....before I tried EI my rotala sp. green would stunt even though the test kit indicated optimal levels.

Thanks


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## hoppycalif (Apr 7, 2005)

The method of letting the green dust algae go through its life cycle before trying to remove it does work. It may take two tries, but it works. I would rather live with an ugly mess in the tank for a couple weeks or so and be done with it, than have to scrape the glass every other day.


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## LindaC (Nov 7, 2005)

I have been wondering what causes this Green Dust Algea. So it's high nitrates then? If I stop dosing KNO3 for a few days, will it go away?

I'm going through hell with this stuff, I have it in both of my tanks pretty badly. It's so bad in my 10 gallon that I can hardly see my fish! I just tested the nitrates in that tank and they're at 40 or higher! 

It is beginning to get on my plants now too, there's just so much of it. I'm on my 2nd week with my 10 gallon tank. I tried to do the same with my 29 gallon and let it go for a week and half and then I did a water change and kept hitting the glass and getting it all over the place so I decided to just clean it, I couldn't stand it anymore. The nitrates in this tank aren't as high though, they're around 20-30 I believe, but I suppose that's high enough.

Where is a good place to keep your nitrates in order to get rid of this stuff? I can't stand it anymore, my tanks would look great if it wasn't for this GDA.


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## BryceM (Nov 6, 2005)

I'm beginning to become a minimalist when it comes to macros, at least with nitrates. Many people will state that high nitrates cause no problems whatsoever, maybe even up to 80 or 100 ppm, but IMO the tank always looks better when it's in the 10-15 ppm range. I have had several bad plant meltdowns with bottoming out on the NO3 though, so it's kind of a balancing act to keep thing on the low end. OTOH, I don't mind phosphates as high as 4 or 5 ppm - at least in my water it seems to work out fine.

Your mileage may vary, but I see no benefit of having nitrates over 20ppm.


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## banderbe (Nov 17, 2005)

Just my two cents, which may not be worth a lot given that I've only been in this hobby for just under a year, but..

I think it's extremely difficult to successfully run a tank lean without the La Motte kits. It's also extremely easy to successfully run a rich tank with no kits at all. At least for people like me who keep smaller tanks (see below).

The rate that the plants use the nutrients grows linearly so the same lean regime will eventually bottom out if the plant mass gets large enough.

This can be really hard to eye-ball especially when you have dense high surface area plants like grasses that can double or triple in volume without needing a trim.

My experience with green dust has been that I cannot seem to tie it to any one variable in my regime. Lean, rich, whatever. It sometimes slows way down, and sometimes goes nuts. I've learned to live with it. I scrape it off and siphon it out with the water and it returns a week later. GIven that it's the only algae I have, I consider myself lucky/blessed.

Also I see threads like this where some folks stress keeping nutrients below such and such a level, and usually they are the ones with the bigger aquariums.

It's been observed by some people like Avalon that bigger tanks are a different beast and that excessive nutrients can be a problem where in a smaller tank, like my 29 gallon, people seem to be able to pay almost no attention to how high the nutrients get and they don't get algae blooms.

It has also been posited that this involves something called "osmotic pressure", and I speculated once that the volume of tank water would have a direct effect on osmotic pressure but as I said it was speculation. Someone with a background in cellular plant biology would be really beneficial around these forums so us lay people could get a better understanding for why some nutrient levels and tank volumes act the way they do.


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## hoppycalif (Apr 7, 2005)

Tom Barr found that GDA was an unusual algae in that its early stage is as a zoospore, a free swimming form of algae. So, when you scrape it off the glass, any that remains in the water is free swimming, so it just seeks out a good site to establish a homestead, and that is normally the glass. When we scrape it off as soon as it gets to be a nuisance we are scraping off zoospores, and the cycle just repeats itself. What I don't understand is, do most or even a lot of algaes go through a zoospore stage, or is what we call GDA a very unique species? And, what would kill it in the zoospore stage? I have had it in almost every aquarium I have ever had.

Edit: Here is the original write-up about GDA being a zoospore form of algae;
[APD] The cure for Green Dust Algae (Akistrodesmus) infestations


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## aquasox (Sep 11, 2005)

Cool link Hoppy 8)


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## LindaC (Nov 7, 2005)

I agree, it's a great thread and makes a lot of sense! Looks like I'll be leaving the GDA alone in my 29 gallon tank too!


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## BSS (May 2, 2006)

I starting 'ignoring' mine about a week ago. I'll report back in another week or two!

Brian.


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## LindaC (Nov 7, 2005)

I'm going into week two with my 10 gallon, I did a 50% water change last night and didn't clean off the glass either, let me tell you, it wasn't easy. This stuff can look almost like a green paste, it's pretty nasty. I'm sure some of the pores got into the water but I'm not letting that deter me, I'm doing this no matter what.

I'm starting my 29 gallon today, I won't clean the glass anymore, not until it's time to scrape it off. I will also report back on both tanks in another week or so.

Good luck!


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## hoppycalif (Apr 7, 2005)

I'm at two weeks and a day with my GDA infestation. The glass algae is much more brownish, with darker spots about a quarter inch in diameter spreading over it. I suspect I could scrape it off safely now, but I need to replace some of the plants and haven't received the bundle I purchased to do that yet. Patience! More valuable than a python!


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## epicfish (Sep 11, 2006)

It's speckled on my glass, green...is that GDA?

My water is a cloudy green and it's not because I'm looking through the glass. Even from above, it's a cloudy green color...what the heck is happening?

Ammonia & nitrites are in check.


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## banderbe (Nov 17, 2005)

epicfish said:


> It's speckled on my glass, green...is that GDA?
> 
> My water is a cloudy green and it's not because I'm looking through the glass. Even from above, it's a cloudy green color...what the heck is happening?
> 
> Ammonia & nitrites are in check.


Sounds like green spot.. GSA.

Raise your phosphates. Works every time.


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