Green Slime

[Scuba Sam]

Hi there, Some advice please. I have some bright green slime in one of my tanks. It comes off in sheets with the magnetic cleaner, and is growing on everything. Low nitrate in the tank, little sunlight, and it is different from regular green algae that I get on my other tanks. Any advice please?

Thanks,

Sam

[alanmin4304]

Sounds like blue/green algae which can be encouraged by low nitrates. It is actually a bacteria (cyanobacteria) and has been frequently discussed here.

[Dixon1990]

I think i have this algae aswell. Is it bad for the tank or fish?

[Caryl]

In a roundabout way it is bad as it indicates an imbalance of nutrients. The slime covers and kills the plants. It is not poisonous to the fish but nor do they eat it.

Try removing as much of it as possible then covering the tank so it is in total blackout for 3 days. Turn off the tank lights of course and do not feed the fish during this period (it will not hurt them). After this time do a thorough siphon of the substrate.

[Scuba Sam]

In a roundabout way it is bad as it indicates an imbalance of nutrients. The slime covers and kills the plants. It is not poisonous to the fish but nor do they eat it.

Try removing as much of it as possible then covering the tank so it is in total blackout for 3 days. Turn off the tank lights of course and do not feed the fish during this period (it will not hurt them). After this time do a thorough siphon of the substrate.

Thanks for your suggestion Caryl - will try that over the weekend.

[Scuba Sam]

Sounds like blue/green algae which can be encouraged by low nitrates. It is actually a bacteria (cyanobacteria) and has been frequently discussed here.

Thanks for your suggestion Alan - low nitrates - is that a bad thing? I don't do as many water changes on this tank because the nitrates are so low but I didn't think that was a negative - can someone explain the water chemistry of this please? I think I can remember my uni chemistry...

[tHEcONCH]

You may also want to try increasing the circulation in the tank - algal spores can't 'take root' if they can't settle.

[Scuba Sam]

Hmm, you may be onto something with increasing circulation - I have just installed a second internal filter and have noticed an improvement over last week or so - the existing filter isn't too flash despite cleaning. More water flow with new one which is a bit oversized for tank.

Thanks.

[jn]

Scuba sam.. I can't explain the chemistry of BGA but evidence suggests that it thrives in environments with low Nitrates and possibly elevated phosphate.

With the no nitrates, plant growth would slow (if you have some.. which I'm assuming you must being that nitrates sound so low).. and I'm guessing even normal algae growth would slow (it is afterall a plant!).. This probably leaves other nutrients unused for the BGA to go crazy on...This type of algae (bacteria actually) is able to fix nitrogen from the air, so when everything else runs out useable nitrate and stops soaking up the other nutrients, the BGA would be able to take advantage of the situation.

(This is all some sort of assumption I've dreamed up based on what little facts I've read over time.. I don't think anyone has been able to prove how or why BGA gets a foothold!) I'd say add a fish or 2 or add some nitrate fertilser after you manage to get rid of the problem (so it doesn't come back)