# Green spot algae



## roscoe (Mar 3, 2006)

Here are the Params:
90 gallon tank about 6 months old
192w powercompact on for 9hrs daily
pressurized co2 with diffusor

ph= 6.4
kh= 5
gh= 8
no3= 10ppm
po4= 3.0ppm

Dosing with Greg Watson ferts.
Kno3- 1/8tsp 3x week
Po4- 1/8tsp 3x week
K- 1tsp 3x week
TE- 20ml 3x week
I currently have a GSA problem. I have to manually remove it from plants every other day. Do I need to add more Po4? The plants are growing great but this algae is an eyesore. Please help.
Thank you


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## hoppycalif (Apr 7, 2005)

Green spot algae usually only appears on the glass or other hard surface, as far as I know. And, if it was on leaves, you couldn't manually remove it. It is hard to scrape off the glass, so it would be virtually impossible to remove from a leaf. Can you show us a picture of the algae you have? Is it a string or thread algae?

I don't think you are dosing nearly enough nitrate, which may be causing blue green algae, a gelatinous blue green sheet algae, which shows up on everything. I dose 1/4 to 3/8 tsp of KNO3 every other day in my 29 gallon tank, with 3.8 watts per gallon, so I think you need to dose around 3/4 to 1 tsp three times a week. Also, you may be low on CO2. The best way I know of to hit a good level of CO2 is to raise the bubble rate a little each day, watching for the fish to be distressed - gathering at the surface, losing color, etc. Then, back off a bit after they show distress, until the act normal. Use that bubble rate and calculated ppm of CO2 as what is right for your water.


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## roscoe (Mar 3, 2006)

Actually, yes, the GSA is on the lower part of the glass as well as the substrate. I don't have a camera so I can't take pics. It is little green spots. It comes off of the glass very easily. It's hard to remove from the leaves. So I need to raise the nitrates? I'll kick the co2 up gradually so my fish don't get stressed.
thanks


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## John N. (Dec 11, 2005)

What has help with my green spot is to increase nitrates. 

But more effectively I think is letting it go through the two week life cycle. You can help rid it faster while you wait by... 

When doing a waterchange, as the tank half empty or so, take a credit card and scrape (horizontal motion, not up and down) the green spot off and wipe off the residue with paper towel, not letting the spores back into the water. 

Green spot eventually goes away for me using that method. 

-John N.


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## banderbe (Nov 17, 2005)

John N. said:


> What has help with my green spot is to increase nitrates.
> 
> But more effectively I think is letting it go through the two week life cycle. You can help rid it faster while you wait by...
> 
> ...


Don't you mean green dust?

Green spot is, I thought, caused by low PO4 and green dust is treated by the 'lifecycle' idea put forward by Tom Barr.


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## John N. (Dec 11, 2005)

Oops! Thanks Barry for catching that typo. You're right, increase your phosphates will reduce Green Spot (hard circular algae spots) and scrape the green dust, or both for that matter during your water change.

-John N.


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## Zapins (Jul 28, 2004)

Yea PO4 for green spot. But Green dust algae is really a tough algae to get rid of once it gets started. Many people seem to have had great difficulty in removing it (me included).

Lowering the lights helped for me... But it looks like your lights are relatively low as it is 190w/90g so just try scrape it off the glass.

Otto cats seem to love eating the stuff. I have a school of 9 of them in my 55 and they seem to take care of any residual green spot algae that tries growing back near the top of the tank where the lights are. If you got a good dozen or so you would probably be set.

May you get rid of it sooner then i did (3months)... good luck!


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## John N. (Dec 11, 2005)

Otos do a good job at scraping the surface, but I find they don't do as well at getting down and dirty so to speak. But they are cool little buggers for a clean up crew, so I would get them anyway.  

Controlling the Photo period and intensity is a good idea, and in my opinion works best at controlling algae of all types, and the easiest thing to manipulate. 

-John N.


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## Zapins (Jul 28, 2004)

I have always had a few ottos in my tanks (usually around 3) but i am amazed at their capabilities when in larger numbers... I had always dismissed them as a viable algae crew, but i have totally changed my mind now and will be incluiding a large school in every tank from now on.

Plus their social antics are quite amusing


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## roscoe (Mar 3, 2006)

Thanks for all of the help everyone  
So what should I increase my Po4 dosing to? Should I just dose 1/2 tsp 3x week and go from there? I have enough otto's in the tank now(about 20).
Thanks


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## hoppycalif (Apr 7, 2005)

I would try 1/4 tsp KH2PO4 for awhile and see if that does it. 1/2 tsp is a lot for that size tank. The few times I have had some GSA I have just increased my 1/16 tsp by rounding over the top of the spoon instead of leveling it, and the GSA went away.


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## roscoe (Mar 3, 2006)

I'll try that. 
Thanks again


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## banderbe (Nov 17, 2005)

John N. said:


> Oops! Thanks Barry for catching that typo. You're right, increase your phosphates will reduce Green Spot (hard circular algae spots) and scrape the green dust, or both for that matter during your water change.
> 
> -John N.


Hey thanks for the rep. John!


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## yildirim (Nov 25, 2004)

Increasing PO4 rates is a bit more tricky than all other nutrients in the tank. You should make the increase slowly and must control all other nutrients as a small increase in PO4 may cause crashes for all other nutrients and esp. for CO2. Otherwise you may have greater problems and a welcome for many kinds of algeas. In your case the problem does not realy seem to be GSA but GDA which are totaly different alg types. You have mentioned that your PO4 reading is at 3 ppm which should be enough for most of the tanks. If I were you I would just start with increased NO3 and CO2 at first instead of PO4.


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## Craig Tarvin (Jul 26, 2005)

roscoe said:


> Thanks for all of the help everyone
> So what should I increase my Po4 dosing to? Should I just dose 1/2 tsp 3x week and go from there? I have enough otto's in the tank now(about 20).
> Thanks


I dose 3/16 tsp of KH2PO4 3x a week in my 75 gallon and have no issues with GSA. I would suggest dosing 3/16 to maybe 1/4 tsp of KH2PO4 3x a week as well as keeping the KNO3 up to at least 3/4 tsp 3x a week, and of course keeping the CO2 levels high (30ppm +).

I think people are scared of dosing PO4 because of old traditions, the PMDD days, etc... I don't think you have to raise the PO4 level slowly, or anything like that. Usually you read posts of people that start to dose PO4 and see good results right away, rather than regretting the decision.


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## roscoe (Mar 3, 2006)

Thanks for all of the advice  
I'll make the proper changes and then update my results.
Thanks


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