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How to get rid of blue-green algae?

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I haven't even noticed, when this blue-green algae first appeared in my freshwater tank. And not it is impossible to get rid of it.

I've already read some info on the topic, like https://www.thesprucepets.com/cyanobacteria-blue-green-algae-1378628 or https://thepets.net/how-to-get-rid-of-blue-green-algae-in-a-freshwater-aquarium/ but want to ask for real experinece to prevent killing beneficial becteria.

Any thoughts?


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Cyano is the absolute worst and every time I get it I end up having to nuke the whole tank to get it to completely go away. Some people have had success with 5 day blackouts, some have had success with adding power heads/air stones to increase flow and oxygenation, some have had success with using products to try to kill it. 

My advice is to first try adding some air stones around the area where you’re getting cyano to increase the dissolved oxygen and the flow. Stagnant areas of built up nutrients usually cause cyano to thrive, so if you remove the stagnant areas, it shouldn’t have any good host spots. Remove as much as you can with a siphon and then make sure that spot doesn’t get stagnant again. Do small, frequent water changes to bring down the nutrient levels to almost nothing. If it has nothing to eat, it should die off. If you have plants, unfortunately this method will probably cause them to suffer a bit, but the cyano is probably outcompeting them anyway. The final thing you can do is a 5 day blackout. This part isn’t fun, but it’s another method of starving the cyano completely. If all of that doesn’t work, then yeah, time to nuke the tank and start over. 

Cyano isn’t necessarily harmful unless you have plants that it is stealing nutrients from, but it’s unsightly and has the potential to release toxic compounds into the water column, which is why it’s necessary to do small, frequent water changes while attempting to kill it. You might even consider adding some activated carbon to your filter to help suck up anything potentially harmful to your livestock. 

If you don’t have plants in your tank yet, I would encourage you to grab some pothos cuttings and stick them in your filter or clip them to the edge of your tank (I usually use aluminum floral wire) so the roots are in the water, sucking up the excess nutrients and preventing the cyano from returning. 

I hope this helps you out some, I wish you the best of luck.

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I had this a few months after setting up my first planted tank and my light was too intense. heard @Cory mention once erythromycin could work. I removed what algae I could and treated the tank with only one dose per tank volume of erythromycin set in the tank for 7 days (remove charcoal if any) then a water change. cyano bacteria gone, did not destroy my cycle either. bacteria and fish were fine. That is what worked for me.

Edited by therealTruthSeeker
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I was experimenting growing moss in a tub and added way too much easy green and light.  I ended up with a gross goo matt of moss and bga.  I threw it all in my shrimp cull tank and they cleaned it all up in about two weeks.  Idk if this is typical but 30 neos in 5g can clean up a lot of soft algae.  Now if they'd only eat staghorn...

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