# Green Dust Algae ODYSSEY



## pacolopezmujica

Well my friends, it's a:
90 gal tank.
160 watts - 10 hours
UV Filter "BIG twister"
PO 0.5 mg/lt
RO water
NO3 0.1ppm
CO2 injected 2 bubbles/sec.
Substrate was ECO complete
Regularly used Diatom powder in my Magnum (this helps but not enough)
And the green dust algae still there no matter water changes.
Actually I could have started a Green DYE business.

Solution 
Drained the whole thing and washed with CLOROX
Yes we cleaned even the smallest item and then start again.
We don't have GDA anymore...

Now I think I have Cyano Bacteria or BGA.
It looks similar to my GDA but this one SMELL and It's not like the GREEN DYE or dusty.
So you see, I think I'm going back at my 56 years to the University and search for a Biology degree and see if I can find a solution. Or turn into HULK and enjoy it.


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## NE

It absolutely sounds like Cyano / BGA.

Your problem is most likely the low nutrition levels, BGA is very active when the NO3 level gets to lo.

PO4 is low but not that bad.
NO3 is way to low, a good starting point should be between 5 and 10, and this is the main problem.
Most certainly you are also low on traces.

There is something called Redfield ratio (N/P) and thats the ratio between N and P,this should be around 10.


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## Bert H

Hey Paco,

A few questions regarding your tank and some comments. It sounds like your tank is out of balance. First, you mention RO water, is that all you're using? Are you adding something to get your hardness levels up, because RO water is pure water with nothing in it. Using CO2, you really need to have a kh of 3 or higher. Plants also need Ca, and Mg, again, which RO water has not. What's your gh?

What are your CO2 levels? Just knowing your bubble rate tells you nothing about your CO2 content of your water.

The cyano (blue-green algae) is brought on by low nitrates, which, as has NE said, you have. You need nitrate levels in the 10-20ppm range. Your phosphate levels need to be in the 2-4ppm range. The Redfield Ratio is something a few folks believe works, personally I don't. You need to have all plant nutrients present in a little excess, ratios are not that important.

Check out the following references to help you out.
http://www.aquatic-plants.org/articles/basics/pages/index.html
http://www.barrreport.com/forums/showthread.php?t=1
http://www.rexgrigg.com/


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## yildirim

I totaly agree with Bert. You should increase the quantities of nutrients and make it *gradualy,* *not all at once*. Instead of testing NO3, PO4 parameters, you should first know the hardness trio and try to maintain them at suggested values.

YILDIRIM


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## banderbe

From what I read, green dust is the only algae that most folks who have defeated the other algaes still deal with.

I am in that boat. By week's end the dust is starting to be noticable on the glass, but it's okay. I wipe it off, do a water change, and it's gone for 5 to 6 days.

I don't suffer any other algae, and dosing Flourish Excel doesn't seem to have any impact on green dust algae.

I figure it's something I have to live with, especially since nobody seems to have a prescription for how to get rid of it.

I can't imagine washing out a tank with bleach would help in the long term, given that the bacteria for green dust are in the air we are breathing right now.


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## plantbrain

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## AaronT

banderbe said:


> From what I read, green dust is the only algae that most folks who have defeated the other algaes still deal with.
> 
> I am in that boat. By week's end the dust is starting to be noticable on the glass, but it's okay. I wipe it off, do a water change, and it's gone for 5 to 6 days.
> 
> I don't suffer any other algae, and dosing Flourish Excel doesn't seem to have any impact on green dust algae.
> 
> I figure it's something I have to live with, especially since nobody seems to have a prescription for how to get rid of it.
> 
> I can't imagine washing out a tank with bleach would help in the long term, given that the bacteria for green dust are in the air we are breathing right now.


This can be fixed by slightly increasing your PO4 dosing. While the ideal ratio of Nitrogen to Phosphorus in a planted tank is about 10:1, your dosing should not be 10:1. Dry dosing a ratio of 3:1 to achieve the desired levels of each nutrient.

Also, Olive Nerite snails will do a tremendous job of cleaning GDA off of the glass.


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## pacolopezmujica

Paco here,
Thanks for your advise, very grateful.
I have to clear something, the original water in this tank 4 weeks ago, was tap water, since then I have done one 1/4 water change with RO water.
Water parameters are the following 
PH 7.4
NO3 = 0
PO4 = 0
Thanks again


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## banderbe

plantbrain said:


> I have a 100% success rate with controlling it in a total of 8 tanks that where inoculated.
> Takes about 2-3 weeks.
> 
> Regards,
> Tom Barr


By doing what?


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## banderbe

AaronT said:


> This can be fixed by slightly increasing your PO4 dosing. While the ideal ratio of Nitrogen to Phosphorus in a planted tank is about 10:1, your dosing should not be 10:1. Dry dosing a ratio of 3:1 to achieve the desired levels of each nutrient.
> 
> Also, Olive Nerite snails will do a tremendous job of cleaning GDA off of the glass.


I dose a solution I made that is 7:1 N to P.

I have seen Tom Barr mention this ratio more than once. I will consider raising PO4 if things don't improve. Either way it's a small nuisance, nothing like hair algae which gives me nightmares.


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## hoppycalif

plantbrain said:


> I have a 100% success rate with controlling it in a total of 8 tanks that where inoculated.
> Takes about 2-3 weeks.
> 
> Regards,
> Tom Barr


Please, pretty please, tell us how you do it.


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## yildirim

Dosing ratios for NPK do not work the same at all tanks as there are some factors (plant types, mass, light, co2,...) in correlation for the uptaking of these nutrients. You may easily be on low side for one or more of them. What works as a charm for nutrients is always to be on the very high ends of the accepted target values esp for P and CO2 (this are the most neglected parameters as target values are usualy kept low, but in fact these are the main issues to promote better plant growth). This way you will always have a good plant growth, and also by having some current in the tank you will always overcome algal problems of any kind.


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## banderbe

Dosing ratios works wonderfully for me. On the other hand, the brute force EI approach of essentially over-dosing all nutrients resulted in lots of algae for me.


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## plantbrain

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## Bert H

> Try this, stop wiping the glass for 2 weeks.
> Observe the film over this time peroid.
> 
> Once GDA goes through it's very tough resistant life stage, the adults are not an issue, it's just the zoospore stage that is an issue. We go after it with cleaning and it maintains the stage/life cycle.
> 
> You leave it alone, and the film will get thick, jelly like, matted, etc as the spores complete that stage. Once the film starts to look pretty patchy, typically at 10-18 days, you wipe it off.


Tom, I, for one, will try that. I just have to get past the stage where I can't stand to look at the green jelly 8-10 days down the road. I shall report back in two weeks time.


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## hoppycalif

While thinking about what to do about my current invasion of GDA I finally remembered my own experience from years ago. I had a 125 gallon tank then, and virtually no knowledge about fertilizing, CO2, or anything else concerning plants. (I was successful with plants anyway.) I had a routine of cleaning the tank weekly, scraping off the GDA, changing about 15% of the water and pruning. I finally got lazy and let the weekly routine drop. The GDA became solid mass on the glass, complete with little grass-like "plants" growing perpendicular to the glass. That finally looked so sickening I went back to my scraping routine. The GDA vanished, and didn't return! I never did scrape the back glass on that tank, so whatever grew there stayed there until the scavengers ate it. At that time I just assumed that the benevolent Gods of Aquaria had smiled on me and forgot about it.

This suggests to me that removing the disgusting mess that is the final growth stage of GDA may not be essential, but removing the early stage by scraping sure isn't the least bit effective. Tom is probably right that if we let it do its thing it will leave us alone later. I'm trying that now.


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## plantbrain

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## banderbe

I am not blaming EI, it did great for getting my tank started.. I am simply observing that using the method I did get lots of algae. There were no doubt other factors at play, like the fact that my tank wasn't heavily planted enough. Sorry if my comment was misleading. Also I was talking about algaes like BBA and BGA which I had plenty of in the first month of my tank's life. I think the GDA would exist regardless of what dosing method one uses.


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## plantbrain

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## nasfish

Hi,

I am doing absolutely nothing on the green dust algae in my 100 liters tank for 12 days now, as suggested.









Question is when to clean it off?. Now is ok?. I can't stand to look that green mess everyday!.

Best Regards


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## Bert H

Update: It's been a couple of weeks and it hasn't changed much over the last 4-5 days. It's kind of 'puckered' up, for lack of a better word. I will scrape it all out and do a major water change next weekend, and we'll see what happens afterwards. Mine isn't anywhere near as thick as nasfish's, and it is riddled with paths where the snails and ottos or sae's took a swipe at it. But I am impressed with the fact that it has stopped getting thicker.


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## hoppycalif

My GDA looks just about like nasfish's photo now, and it has been about two weeks now. The fish are now grazing on the algae! And, as Bert mentioned, I have lots of snail tracks in it. If anything it seems a bit more transparent now, but just barely. Also, I have some darker green veins in it. I don't see what I would call puckering yet, and I have to stretch a point to call it jelly like. But, I am so sick of looking at the mess I plan to remove it in a couple more days, and do a big water change. The tension is from knowing if I do this too soon I am back to waiting another 2+ weeks, watching green **** instead of plants. Some plants I haven't seen for 2 weeks now!


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## plantbrain

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## upikabu

plantbrain said:


> You should see less growth, more patches or bare tank glass etc, I did not wipe one tank at all, it finally cleared up on it's own.
> 
> 2-3 weeks seems about the right time frame.
> 
> The hard part is leaving the tank alone.


Hi Tom,
I have a question on this approach as I'm battling this algae at present. Should I continue to dose ferts (regular EI amounts) & do the weekly water changes as usual during these 2-3 weeks? So do everything normally except wiping the glass? TIA!


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## Bert H

> Should I continue to dose ferts (regular EI amounts) & do the weekly water changes as usual during these 2-3 weeks?


Yes, do everything as you normally would, just don't wipe down the glass when you do your water changes, etc.


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## plantbrain

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## hoppycalif

Today was the big day! I scraped off the green mess on my glass. This is about 20 days from when I last scraped it, and 18-19 days since I first saw that my last scraping did no good at all. The GDA had gotten considerably thinner, so much so that I could see the plants through it, so I had to assume that I was in the adult stage of the algae growth cycle.

In addition to scraping the glass on two sides - I left two alone just to see what happens - I also made major changes to my filtration and CO2 injection. I got a Maxijet 600 and a sponge filter for it, installed it upside down with the CO2 tube sticking down into the sponge support grid. Then I removed my Fluval filter entirely, removed the little minijet pump that I had used for CO2 mist, and am now using the powerhead as my only filtration. That removed the inlet and outlet tubes for the Fluval, and leaves me with no place where debris can clog up the suction, a possible factor in other algae attacks. So far the CO2 mist looks great and the water cleaned up very nicely.

Of course, now I will be walking on eggs for a week waiting to see if the GDA returns to the glass. Today was the first I have had a good look at my plants, shrimp and fish in over two weeks!


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## Bert H

Update: I, also scraped yesterday! It appeared to be becoming visibly thinner, as Hoppy's was. Fingers crossed, by Thursday I'll know whether there's success or not.



> So is it time yet Bert?


 Tom, we're having a party at the house next wkd, and the word from the boss was that the tank had to look good.  So, I figured, it was time. But if it turns out that it wasn't, you're on.


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## plantbrain

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## banderbe

Why does GDA not come back just because some spores were allowed to go through their entire lifecycle?

That's the part I don't understand.

Also I will be trying this method starting yesterday. Did my water change but didn't wipe down the glass like usual..


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## Bert H

> Why does GDA not come back just because some spores were allowed to go through their entire lifecycle?


I am guessing here, but it would stand to reason that once the spores have gone their life cycle, they will then revert to a dormant phase, until something triggers them to start the process over again.


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## hoppycalif

banderbe said:


> Why does GDA not come back just because some spores were allowed to go through their entire lifecycle?
> 
> That's the part I don't understand.
> 
> Also I will be trying this method starting yesterday. Did my water change but didn't wipe down the glass like usual..


Green dust algae on the glass is an algae still in the zoospore stage, meaning it is a free swimming algae that is extremely robust. All algal spores are able to survive almost anything from boiling to freezing to drying out. So, when we clean off the GDA the spores left in the water, and there are always some left, just swim around and find the nice smooth glass again, where they again stop and start a new bloom. But, the adult stage of this algae is not nearly as robust, and is not free swimming. So, letting it complete its life cycle to the adult stage lets us have a very much improved chance to kill it off. I assume the adult algae releases sporess again before it dies, but until something triggers those to start the cycle over again the tank is free of that algae. This is, I think, how Tom Barr explained it. The only part that confuses me is why the stuff never seems to start over again from the newly released zoospores.

My tank is now two days into the post-scrape period. The glass seems to be getting a bit cloudy again - bad news. I plan to do another water change today and wipe it down good.


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## hoppycalif

Later today I checked my "cloudy" tank glass more closely - it is definitely the GDA starting over again. Not welcome news. But, I suspect I know why it has returned. A week ago I did my routine water change, but the siphon rubbed a bit on the inside of the glass at one point. When I got done I noticed there was a 3 or 4 square inch of clear glass there, right at the top of the tank, at the water line almost. I think that was the equivalent of scraping off the GDA too soon, so the spores just reestablished their growth and it blended in with the older algae. When I scraped it all off two days ago, I was scraping both old algae and young algae. Now the young apparently swam around and recolonized the glass. If I am correct, we need to treat the stuff like a newborn baby - no touchy, no feely, and definitely no scrapee!

I was too busy today to clean the glass and do a water change, so I plan to try again tomorrow. Do tears adversely affect the fish?


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## Bert H

> I was too busy today to clean the glass and do a water change, so I plan to try again tomorrow. Do tears adversely affect the fish?


 Oh, no, Hoppy! I'm keeping my fingers crossed - so far, I don't see anything on the glass.


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## banderbe

hoppycalif said:


> The only part that confuses me is why the stuff never seems to start over again from the newly released zoospores.


Or why it doesn't start over again from the spores that are naturally in the air we are breathing.

That's how we get the GDA in the first place.. seems to me it would just settle out of the air, into the water, and start growing just like always.

Only thing I could think up was that maybe the adult stage leaves behind a marker that tells new spores not to grow there.. sort of an evolutionary advantage to encourage ever-greater geographic dispersal. Of course I'm totally speculating and I am not a biologist or a scientist unless you count computer science!

Who knows but if it works it works.. we shall see!


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## nasfish

Hi,

Finally, after weeks, looking at that ugly green mess, I cleaned it on Monday, with almost 80% water change. A lot of works, using sponge and some razor blade, like weeks of works, done in couple of hours. On Tuesday, do another 50% water change after another cleaning (even though the tank looks clean), Wednesday, another 25% water change and today, everything is crystal clear. Hope the GDA won't come back. Keeping my fingers crossed.

Best Regards


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## hoppycalif

I'm starting a second three week try at letting the GDA go thru its life cycle. This time I will totally neglect the tank except for light, ferts, and topping off the water. I'm now pretty sure my first attempt failed because I accidentally scraped some of it off with the siphon tube during a water change. That portion of the glass regrew more algae, but it would have remained at the zoospore level for the week before I finally scraped the whole glass, and those little beauties then recolonized the glass. Has anyone else noticed that GDA can have another more appropriate meaning than green dust algae?


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## upikabu

Well, here's another failed attempt at tackling GDA after supposedly letting it go through its lifecycle (at least my assumption). I let the tank go for 14 days without wiping the glass (the green dust turned into a gooey-looking mess). Last Sunday I proceeded to wiped the mess using a sponge while doing a water change, trying my best to contain the mess in the sponge. I guess I didn't succeed as 2 days later a thin layer of green dust started to accumulate on the glass again. :mad2:

Maybe I didn't let it go long enough. I wonder if running a quick filter attached to the powerhead during glass wiping would help in trapping the free spores and reducing them from the water column?


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## nasfish

Same thing here. After two days, GDA starts to appear again. I let the tank go for about 18 days. But this time round, GDA not as thick as before. Right now, I am starting a second try, maybe leave it alone a little bit longer.

Thanks


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## Bert H

Follow up - well, it didn't go away completely. Actually, it is improved by about 50%. The film which re-formed was only about half of what I was dealing with weekly before. It will have to take a backseat to other stuff I have going on currently. High school graduation party this wkd and I am under strict orders that the tanks have to look good. Where I might have messed up is in not having cleaned out the filter when I did the scraping. Oh, well, the saga continues...


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## JimM

I also have a constant battle with this GDA. Each waterchange I turn off my filter then scrape about the lower 20% of glass before removing any water, lower my water lvl to that 20% mark and wipe the glass with clean paper towels to remove the upper 80% being careful not to let any drip back into the water.. this only serves to make its reappearance a bit slower, It always comes back.. also it seems to come back faster with more nitrate. I really dont see how letting it grow out before cleaning it can do anything besides make the tank look bad, in a life cycle wont there always be young zoospores?

anyway, I think the best solution is.. bushy nose pleco!.. I never had this problem before I removed one from this tank.


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## hoppycalif

It is hard to believe that letting GDA live out it's life cycle can permanently remove it from our tanks. But, if it does, it is a really great idea! So, I am willing to take the chance. All I lose is three weeks or less of the ability to enjoy looking at my tank.

I'm in the second week of letting mine grow out now. The GDA is thinner this time than it was the first time I tried this, and it is now getting still thinner - approximately day 11 of the grow out.


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## Zapins

I got rid of it in my tanks by lowering the light down to 2 wpg and just keeping up with my normal fert doses - no WC for about a month. I think its still there, but its nearly undetectable.

I would like to add that i had this stuff for months and every cleaning i tried failed horribly and it came back with a vengeance. I tried changing the nutrients, leaving it for days without doing anything at all. But i really believe that reducing the light as well as not doing any WC/scraping kills this stuff off. 

I can't tell you how happy i am that it is gone now, i was on the brink of torching my tank...


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## hoppycalif

The title of this thread is GDA Odyssey - and an odyssey is a long trying journey. So......to continue the journey:
I have just reached the end of my second week of trying to let the GDA live out its cycle. It is now much thinner, in that I can see a lot more thru the front glass, but it is thicker where it is on the glass. I think this must be the final adult stage where I should be able to clean it off the glass and say Sayonara to it. But, I have a failure of nerve! So, I'm going to let it go a full three weeks or until 90% of it falls off the glass by itself. Meanwhile, I am growing the biggest pond snails I have yet seen in a planted tank! This stuff is like continuous steak dinners to the snails. And, my oto only has to eat a few minutes a day to fill up his gas tank. See - didn't your mother always say there is a good side to everything?


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## IUnknown

Ran into this problem (around post #29),
http://www.aquaticplantcentral.com/...da-style-20-gallon-3.html?highlight=20+gallon

Be patient, at least this is one algae that you actually do something about and never see it again.


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## hoppycalif

To continue my odyssey: I am now on day 19 of the life cycle of my GDA, and it has almost all vanished from the glass. The pond snails continue to feast on what's left, and the oto joins them when it gets hungry, which isn't often. If all goes as planned today, I will do a clean up and water change today. According to the theory I will never again in this lifetime have to look at a green rectangle instead of an aquascape! My fingers are so crossed they are cramping.


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## Bert H

Hoppy, does it grow throughout the glass? I ask, because on mine, which is now starting its second week again, I don't have any on the upper half of the tank, which co-incides with where I draw the water down to when I do my water changes. It's only on the bottom half.


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## IUnknown

> According to the theory I will never again in this lifetime have to look at a green rectangle instead of an aquascape! My fingers are so crossed they are cramping.


That is until you get some plants from a friend and reintroduce it to your tank.


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## hoppycalif

Bert H said:


> Hoppy, does it grow throughout the glass? I ask, because on mine, which is now starting its second week again, I don't have any on the upper half of the tank, which co-incides with where I draw the water down to when I do my water changes. It's only on the bottom half.


My episodes have all begun with a slight green haze on the middle part of the glass, which spreads and gets thicker on all of the glass, both ends, the front and the back. This time was no different. The thickness isn't uniform by any means. Where the Kleiner Bar sword shades the front glass it remained pretty thin. Where the powerhead blows out CO2 bubbles and water against the glass it got thickest of all, even waving in the "breeze".

This was my second attempt to wait thru the life cycle. The first time I accidentally scraped some off during a water change, and it came back when I ran thru the cycle and cleaned it off. But, this episode hasn't been as thick as the last one. It is on all of the glass, but some areas I could slightly see thru, where the last one was such that I couldn't see anything at all inside.

I didn't get around to cleaning the tank today, so tomorrow is now scheduled to be the big day.


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## IUnknown

When I cleaned my glass I emptied the tank so there was no water and then used paper towels to get the algae off without spreading it.


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## pacolopezmujica

Well, it has been almost 2 months since I started this thread and would like to send a picture of my tank at this moment. I got rid of BGA but still have places of Green Dust Algae or what we call it around here, TEMPERA, cause it dyes your fingers.
I'm using my Magnum Diatom filter with the diatom powder. Hosing the pebbles that are painted with the tempera, cleaning them, not many GDA on plants, but if it appears, I'll shake it and the Diatom filter absorb it. I haven't eradicate it but I consider it controlled. I'm doing weekly 1/3 water changes and using half RO and half Tap water.
Thanks for all your help and I'm trying to find here in Puerto Rico KNO3, see if that works. 
Thank you all,
Paco
We shall overcome!


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## hoppycalif

One last report on my own GDA odyssey - I hope. After exacly three weeks of neglecting the GDA I was left with a very thin haze of it, splotched by snail tracks. I did a thorough cleaning of the glass, plant pruning, and water change, but left the back glass alone. Now, after 4 more days I have no GDA haze forming on the glass! Usually I can see the haze starting over again after only two days or less. So, I am ready to declare victory over GDA!

For anyone who hasn't been following this, the method is to just ignore the GDA, don't disturb it at all for two to three weeks. That lets it live out its natural life cycle and be eaten by the snails and fish. Then you clean it off thoroughly, keeping as much as possible of the scrapings out of the tank water. The GDA should not return again. I found that if you remove any of the GDA before the life cycle is over, the cleaned area is just re-colonized by GDA spores and you have to start the two to three week wait all over again.


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## IUnknown

I wish I had known about this a year ago. I ran a tank for a long time doing everything right, but having this algae come back every week. Drove me crazy.


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## upikabu

Thanks for the info, Hoppy! I can definitely vouch for 2 weeks or less being too early to start cleaning the glass. Also if you see green algae on the surface of plant leaves, don't clean it, leave it alone (I think it's also GDA even though it looks different than the glass one). I'm on my 3rd attempt now after the first 2 attempts failed (14 days and 10 days). The algae is thinner everytime, but it still came back after a few days. Will let it go for 3 weeks this time.


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## hoppycalif

My plants were also covered with a green fuzzy algae while the GDA was active, but that went away along with the GDA. I think it is GDA too. So, apparently the "fix" for that green fuzz is to ignore it and let it live out its life cycle too.


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## asincero

I have a question. Would filtering the tank with a diatom filter be able to get rid of the GDA spores? Or are they smaller than 1 micron? I hate having to scrub the tank down every week, but letting the 'ol Vortex run overnight once a week is certainly no big deal.


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## hoppycalif

asincero said:


> I have a question. Would filtering the tank with a diatom filter be able to get rid of the GDA spores? Or are they smaller than 1 micron? I hate having to scrub the tank down every week, but letting the 'ol Vortex run overnight once a week is certainly no big deal.


I can't answer the question, but I do know that GDA is usually a reccurrent problem when people get it, and I hadn't read any success stories for those who tried other methods. It would help a lot of people if you try this for a month or so and report back how it worked.


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## upikabu

I didn't use a diatom filter, but tried a similar method using a quick filter attached to a Hagen powerhead. That didn't work.  But, I can say that leaving it alone for 2-3 weeks seems to be working best. I'm on my 3rd ignore attempt right now (previous two attempts only up to 14 days max, and GDA returned each time, albeit not as bad as before), and after a little over 2 weeks, I only see very small patches of GDA left on the glass. It definitely seemed to have cleared up on its own.


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## Zapins

Diatom filters do not help to slow its growth neither do UV lights. I used both a vortex diatom filter and a 13w UV sterilizer on my 55g tank during the outbreak and it did nothing.

Lowering the light as I said before seems to severely limit its growth and make things more tolerable as well as leaving it for 2-3 weeks.


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## asincero

Do dwarf otos eat this kind of algae?


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## Bert H

> Do dwarf otos eat this kind of algae?


I've never heard of 'dwarf' ottos, but my regular ottos don't do much with it.

BTW, I scraped it last night after another 3+ weeks. It was much less than the time before, so I'm keeping my fingers crossed.


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## asincero

Bert H said:


> I've never heard of 'dwarf' ottos, but my regular ottos don't do much with it.


Just another name for otocinclus affinus aka pygmy suckermouth catfish aka dwarf sucker.

So your ottos didn't do much to the GDA? Bummer ... I was thinking of getting some too.


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## hoppycalif

The primary grazers on my GDA were the common pond snails, which grew about 5 times as big as I have seen before. But, the oto also had a feast. Having only one, he didn't make nearly the big dent in the supply that the snails made. The guppies also spent a lot of time picking off pieces of it. Apparently GDA is a nutritious vegetable treat. The GDA(?) which showed up as green fuzz on the plants disappeared with the GDA on the glass, but I don't know if it was eaten or what.


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## asincero

hoppycalif said:


> The primary grazers on my GDA were the common pond snails, which grew about 5 times as big as I have seen before. But, the oto also had a feast. Having only one, he didn't make nearly the big dent in the supply that the snails made. The guppies also spent a lot of time picking off pieces of it. Apparently GDA is a nutritious vegetable treat. The GDA(?) which showed up as green fuzz on the plants disappeared with the GDA on the glass, but I don't know if it was eaten or what.


Yes, I noticed when I had snails I hardly ever saw any significant GDA accumulation on the glass. But, back then I perceived the snail infestation as a "problem", so I bought 3 yo-yo loaches to handle this problem. So now, no more snails but now algae. D'oh!

I wonder if I could get bigger snails that will eat the GDA but won't get eaten by the loaches.

Anyhow, I went ahead and bought some otocinculus. I think I lucked out too because I got so-called "Giant Otocinculus". Apparently, this species is somewhat on the rare side. We'll see how well these guys will handle the GDA.


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## John P.

Nerite snails?


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## asincero

John P. said:


> Nerite snails?


Hmm .. I just Googled for them and they sound terrific. They eat algae. They don't eat plants. And they don't reproduce in freshwater. Whats not to love?

However, I'm afraid my yo-yos might make a meal out of them. I read these snails grow to 1/2" to 1". That might be too big for the yo-yo, but I don't know for sure. Only one way to find out!


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## John P.

The only reason I haven't used them is they lay eggs often


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## banderbe

AFM had an article recently on snails and other critters and apparently you can keep your snail population at bay by simply not over-feeding the tank. Never heard that before but it makes sense.


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## asincero

John P. said:


> The only reason I haven't used them is they lay eggs often


Oh? Why is that a bad thing? Do they pollute the water or something? I read they don't hatch in freshwater.

Maybe my yo-yo loaches could eat the eggs if they don't eat the snails.


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## ranmasatome

it makes small white spots everywhere in your tank that is a pita to remove..and i mean everywhere.. very unsightly.


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## 247Plants

Well just an update on my tank....

After weeks of the green dust algae my glass is 90% gone and clear except for the white residue it leaves.....It was a tough one to wait out but im glad I did!

Sucess!!! Thanks Tom Barr even though he wont see this!


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## Zapins

My ottos really did a number on GDA. I have 9 of them in my 55 and they keep the place squeaky clean


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## banderbe

Ottos eat all your GDA?? I have three in a 29 and they don't even make a dent.

Also for those without the patience for Barr's method, I seem to have found something that seems marginally effective.

Overdose Excel to your tank and then immediately after you do that scrape all the glass- I use a credit card. I thought this might work to kill lots of the spores and it seems to because this week the GDA is coming back way slower, but alas it is still coming back. I am going to repeat this process and see if over a few weeks I can't eradicate it completely.. I doubt it will work.. but it's worth trying.. I just couldn't stomach looking at my poor tank all covered with green funk on the glass.. was too much to handle for more than a couple weeks..


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## Zapins

Well no, they did not eat all the algae. I first reduced intensity and duration of light. Then after a few days the algae started to fizzle out in most areas in the tank. However it lingered up near the top of the tank where the light was most intense. Then I added ottos.

The ottos ate the remainder and since then it has not come back. So the algae took a beating from less light and then the ottos ate the rest of it and I assume keep it from growing up near the top.

What a horrible algae. I am soooo glad it has gone... It really was painful to see it every day...


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## Gumby

banderbe said:


> Ottos eat all your GDA?? I have three in a 29 and they don't even make a dent.
> 
> Also for those without the patience for Barr's method, I seem to have found something that seems marginally effective.
> 
> Overdose Excel to your tank and then immediately after you do that scrape all the glass- I use a credit card. I thought this might work to kill lots of the spores and it seems to because this week the GDA is coming back way slower, but alas it is still coming back. I am going to repeat this process and see if over a few weeks I can't eradicate it completely.. I doubt it will work.. but it's worth trying.. I just couldn't stomach looking at my poor tank all covered with green funk on the glass.. was too much to handle for more than a couple weeks..


Interesting you say this. I let the GDA get to almost the end stage... Thick film on the glass that swayed in the current, then it started to die from the top of the tank down, just turning white. The "tufts" of it on the driftwood and what was growing on the plants had started to bleach out too. So I scraped it off the glass with a credit card and did a 3x OD with Excel. I was thinking "hey, Excel worked for BBA, I'll try it on this crap."

I'll let you know how it went. I won't be around to see it personally, as I'm moving, but I'll ask my mother to give me a report on how it's doing.

"GDA" is exactly what I'd call this stuff... but sometimes the GD doesn't stand for "green dust," if you get my drift!


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## John P.

I've found this works to lessen GDA

1) Let the GDA build up, 
2) Scrape the glass,
3) Do a large water change
4) Stop EI dosing/add only micros and potassium
5) Repeat 2, 3, & 4.


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## Ljeto

As some suggest, lowering the light does help prevent/slow down GDA. On the other hand, how do we grow light-intensive plants? Specifically, I have HM (grows like weed), some HC, and as of recently glosso (it's a 375 L / cca 100 g tank). In my earlier (lower light) set-ups I never had GDA problems, however, now with lots of T5s, GDA is my biggest enemy. 

And just to share with you, Alternathera R. seems to be a real magnet for this menace - Alternathera grows fast, but only the newest leaves are not plagued with GDA. I am at a point where I am considering kicking it out altogether. I am hoping that once GDA goes off the glass, it will also leave Alternathera alone.


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## Ljeto

I would like to join the club of those who kicked-out GDA, using the 'do-not-disturb for 4 weeks' method. After 1 month, I wiped the glass, did 20% water change, and 10 days now my glass is spotless (well maybe a few dots of GSA). GDA in some form is still on my rear glass, but I don't mind.

I still have a minor case of BBA, but CO2 and Easy Carbo should take care of that.


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## TarantulaGuy

Ugh, I just redid a 29 after a year or so of neglect with no light fixture or CO2. I have been constantly battling this GDA (not the nice abbreviation either) since then for the past month or so. Glad I stumbled across this thread, I'm going to try the "wait and see and then scrape" approach. If it works, I'll post it up on here. I really hope it works, this stuff is ridiculous. I know this is an older thread, but I think it's a good one to keep going, especially since this is a common algae and this strategy apparently works.


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## TarantulaGuy

Well, about halfway through this month long business, and I'm already sick and tired of staring at a green box. I miss my plants, and my fish  Hopefully, when this is all said and done, it will work; I don't think I can suffer through another month of this algae. I cut back my lighting by half, that room gets a lot of sunlight (and in Alaska in the summer, that is a *lot* of sunlight) and I hope that'll help. I should post a picture of it, the algae is waving in the water-breeze. That being said, it's given me lots of time to catch up on my 10 gal natural tank and give it some much needed care.


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