Black algae like growth

[Spender]

Hi

I have had my topical freshwater fish tank set up for around 4 years with almost no problems until about a year ago. In the last year I have been struggling against some kind of black algae, it covers every surface of the tank including plants, gravel, glass, rocks etc, as soon as I scrape it off it comes back again within a couple of days. It has a peculiar odour as well kinda like you get in a damp forest in Autum if that makes sense. I do around 10% water change weekly, have replaced my lights for new ones and reduced the amount of time the lights are on to around 5 hours a day. My tank is 180 litres with two internal filters I bought a tea kit and my ph is 7, nitrite 0, nitrate 0, ammonia 0, chlorine 0. It doesn't seem to matter what I do this stuff always comes back, another strange thing is if I put any live bearers in the tank they always die within 3 days or so, my existing fish are fine.

I have posted a picture to try and show the problem

Kind regards

John




That picture was taken just a few days after scrubbing those rocks completely clean.

 

[aqua_chem]

Its blue green algae (cyanobacteria). What are your nitrates testing at?

 

[Spender]

Hi

Thanks for the reply, I have just tested again with my api master kit and my tetra 7 in 1 kit and both are showing nitrates at 0 ppm.

Cheers

John

 

[aqua_chem]

Just to make sure, you shook it right? But that is what I suspected because...

BGA thrives in low nitrate environments. You need to find a way to bring up your nitrates or it will continue to do well. Unfortunately, Ive found that once you bottom out on nitrates, simply fixing the problem wont make it go away on its own. You can try scrubbing it off, a three day blackout, or if it gets particularly bad, a dosebif erythromyacin.

 

[Spender]

Ok thanks for the advice. I will research how to increase the nitrates, I have been plagued by this for over a year, my tank is not so bad at the moment but I have been doing some cleaning everyday to keep it in check, to be honest I'm on the point of giving up with it. The antibiotic you suggest is not easy to source here in the uk.

Cheers

John

 

[aqua_chem]

It's sold as Maracyn I in the states, which may or may not be the same thing across the pond.

What kind of light and fertilizing regimen do you have? Also, with as much specificity as possible, what kind of plants do you have?

 

[Spender]

Hi again

I'm not sure exactly what plants I have but I do know I have some amazon swords, some densa, duck weed on the surface along with some other floating plants but these are all recent additions, I havent been using any fertiliser at all.

 

[aqua_chem]

What kind of light?

 

[Spender]

Two one metre fluorescent lamps from aqua one, one a pinkish colour and one more of a white colour, both less than 3 months old. I have about 15 plants in my tank in total, one angel fish, two rams and four clown loaches.

 

[aqua_chem]

Two one metre fluorescent lamps from aqua one, one a pinkish colour and one more of a white colour, both less than 3 months old. I have about 15 plants in my tank in total, one angel fish, two rams and four clown loaches.

T8, T12, T5, etc? That does sound like a light bioload for a decently planted tank without ferts.

 

[Spender]

Lights are T5 it's a juwel 180 litre tank with the installed juwel filter and a extra fluval 2+ filter. I have tried to introduce different live bearers but they always die.

 

[aqua_chem]

Yea, so it sounds like you have a low nutrient/moderate light setup going. You might consider getting dry ferts if you can. Gives you a huge degree of control and will save money compared to buying liquid ferts.

 

[Spender]

Ok thanks for the advice, I will do some research as this side of fish keeping is completely new to me, I was always told zero ammonia,nitrates, nitrites was a good thing but its obviously far more complex than that. I have here an aqua one 1200 external filter that I have been holding off installing until I cured the black algae problem. Thanks for taking the time to give me advice I appreciate all the help I can't get. It's 2am here so I'm off too bed now

Cheers for now

John

 

[aqua_chem]

Zero on all is idealfor fish. Plants depend on the nitrates though.

 

[Spender]

Ok on plants but forgive my ignorance but wouldn't higher nitrates help this blue green algae also?