What is this algae and how do I get rid of it?

[koleary317]

Hello. In our 29-gallon tank with now 3 African Cichlids, we had a fuzzy looking blueish green and terrible smelling algae start growing in our tank two weeks ago to the day. I took everything out of the tank, scrubbed all the decorations with warm water, siphoned the sand and did a water change and that seemed to do the trick, until I woke up this morning and although the smell isn’t present right now, I can see little patches of a blueish green algae starting to pop up again. I’d like to get a handle on it now before it stinks up the house again. Any suggestions? I have pictures for reference from two weeks ago. The current patches are too small to discern in a picture. Thanks in advance for any help and advice!

 

[Colin_T]

Blue green algae (Cyanobacter bacteria). A photosynthetic bacteria that loves red light, nutrients, low oxygen levels and slow water movement.

Big daily water changes, increased water movement and aeration, reducing dry food, and making sure the lights are around 6500K normally helps.

If there's no live plants, try adding some floating plants to use nutrients and reduce the light getting to the bacteria.

In really bad cases you can use Ultralife Blue Green Slime Stain Remover

Amazon.com

 

[koleary317]

Thank you! Is this blue green algae harmful to the fish?

 

[Uberhoust]

This is from my personal experience and may differ from other advice you get.

I have had a major fight with cyanobacteria recently in one of my aquariums. The tank was very clean, and had low nutrient loading but for some reason the cyanobacteria kept coming back.

I thought the issue might have been the substrate and I was going to change it but instead I came across some literature from the aquarium scapers? groups that suggested that the cyanobacteria becomes an issue in two cases, nutrient restricted tanks and tanks with excessive nutrients.

I got rid of my issue, I believe, by being a bit more relaxed about the nutrients in tank. I slightly reduced the water change amount, typcially I change at least 50% but often nearly 75% gets replaced, I only removed the cyanobacteria during water changes, allowing other algaes to grow on the back and side of the aquarium.

Slowly over time I found I got more green algaes in the tank which cleaned off the glass easily, and less cyanobacteria, the problem tank is now over a year old but still does not cyanobacteria in it (noticeably anyways).

Your tank doesn't look heavily stocked and clean. You might just need to keep cleaning up the cyanobacteria, while letting more useful green algaes a chance to establish.

I have also tried the Blue Green Stain remover, it worked for a bit then came back again.

 

[Byron]

It might be my eyes, but any cyanobacteria I have had does not look like these photos. This looks more like algae. You will always have algae in a fish tank under light. Someone suggested floating plants...good. Or less light.

 

[Uberhoust]

This looks more like algae.

I am pretty sure it is a cyanobacteria and very close to what I have had to deal with in the past. I haven't encountered a green algae with the same sort of presentation on the surface of the gravel closest being diatoms. I would expect it is from the genus Oscillatoria, which could be confirmed with a microscope, and which has a high range of colors.

 

[Colin_T]

Thank you! Is this blue green algae harmful to the fish?

In large amounts it can poison things in the tank. There isn't a lot in your tank so it's not a major issue currently. Fish, shrimp and snails that live near the bottom are more likely to suffer from it.

The blue green algae is the dark green coloured stuff on the sand and rocks.

The brown algae on the top rocks looks like brown algae and is nothing to worry about.

Cyanobacteria has a musty smell to it and often lifts off in sheets or films.