# Blue Green Algae - Bloom with CO2 but too little ferts?



## Reckon (Jul 25, 2012)

Hey, in my 10gal tank I just noticed a bloom in Cyanobacteria in the last 3ish days.
I just hooked up CO2 pushing through about 1 bubble every 2 secs around the same time as the bacteria growth.

I conciously avoid overfeeding. 
But I checked the nutrient levels in the tank. < 5ppm NO3; near 0 ppm PO4; and 0 NH3/NH4. 
I only have a few fish in this tank (as seen in my sig), for flora there is frogbit, various mosses and crypt plants (about 40 leaves).
pH 7. kH 4; gH 5.
Photoperiod: 8 hours. 
Water change every 2 weeks.


The tank is getting torn down anyways so the blue green algae isn't really a big deal. But I was just curious for learning sake.
I used to think that cyano is a result of too much light or poor water conditions but with what I manage in this tank I'm surprised to see Cyano.
Think the imbalance of too little ferts but CO2 injection is causing the cyano to grow?

Any ideas anyone?


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## 2wheelsx2 (Apr 21, 2010)

It's from a lack of nitrates. In CO2 injected tanks BGA will appear with lack of nitrates.


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## crimper (Oct 20, 2010)

Hi Reckon,

+1 on 2wheels2x. I solved my BGA issues by pumping KNO3 on my 90G Planted tank.


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## discuspaul (Jul 2, 2010)

Cyanobacteria is also promoted/helped along by insufficient water circulation in the bottom portions of a tank - it thrives in low, or no, oxygen areas, and in pockets where, e.g., decomposing plant matter, detritus, etc. builds up.
Spot dosing with H202 (hydrogen peroxide), along with a good substrate clean-up, and improved circulation will usually make it disappear. ( A circulation pump, properly positioned, will do the job.)


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