Fighting Black Algae

[BryceHockey]

Over the past few weeks my tank (see signature for size and stocking) has been slowly growing black algae on the live plants and it's certainly not pretty. I read on a few sites the recommendation of soaking the plants in a water bleach solution of bleach being only 1 part to 20 parts water. As instructed I soaked the wisteria with the most black algae for only 2 minutes, and then rinsed it very well to be sure that no bleach would get in the tank and hurt the fish. After this the plant was soaked in a bucket of clean water for 10 minutes, just to be safe.

That wisteria has been very weak since, although it has some leaves that are still green it almost has a rotting look (the plant had been beautiful for a few months before this happened). Other plants in the tank, including just a few smaller wisterias and a rotala indica also have the algae and I do not want to destroy them. I've tried trimming the affected leaves off, but each week more leaves are growing it.

Any suggestions for ending this black algae?

 

[aaronnorth]

It sounds like Black brush algae (BBA). It is caused by poor CO2 and/ or poor circulation.

you will need to increase your levels of CO2 and/or improve water circulation around the plants . Scrub and cut off as much as you can first. Increase levels slowly to 30ppm or more but watch the fish to see if they are respiring heavily. Make sure you have good water flow around the whole tank along with some good surface movement. Adding a powerhead will help - aim for 10x turnover. (CO2 part only apllies if you are injecting CO2]
If you have a low light tank without CO2 injection then not doing any water changes will help. This is because tap water often has lots of CO2 dissolved in it which causes CO2 levels in your tank to fluctuate. The algae respond to this a lot quicker than the plants do.

Overdosing Flourish Excel/ Easylife Easycarbo will clear it up.

 

[BryceHockey]

Thanks for the response Aaron. After I posted I saw your link to the algae guide with that description. I do not currently inject CO2, both types of plants grow rapidly without much extra help. I've been dosing 1 ml of Flourish once a week, would doing this twice a week with regular Flourish (not Excel) help anymore? I'll try to go a bit longer than once a week with water changes.

Also, I have a lot of surface and water movement from the filter and air stone.

 

[aaronnorth]

If the plants are growing fine and showing no signs of nutrient defficiencies then keep the dose as it is.

What filters and/ or powerheads do you have on the tank?

 

[BryceHockey]

There is no powerhead, but the filter is a Aqueon Power Filter 10 (flow rate is 100 gallons per hour).

 

[aaronnorth]

To get rid of it i would buy some easycarbo or excel and dose it daily at the reccomended dose OR you can gradually raise the dose to 3x overdose which will kill it off quicker.

You can pour the dose into the tank if it is everywhere or you can "spot dose" which means get a pippette/ syringe and squirting the daily dose onto the infected areas - this is a more efficient way.

 

[BryceHockey]

To get rid of it i would buy some easycarbo or excel and dose it daily at the reccomended dose OR you can gradually raise the dose to 3x overdose which will kill it off quicker.

You can pour the dose into the tank if it is everywhere or you can "spot dose" which means get a pippette/ syringe and squirting the daily dose onto the infected areas - this is a more efficient way.

Ok thank you, I will try to buy those very soon.

I would assume that overdosing will not harm the fish? If there's a risk of the fish getting sick from putting too much in the water, I wouldn't want to do it.

 

[aaronnorth]

I have sensitive species (otocinclus and shrimp) and i have dosed 5x without upping the dose gradually, but i know i am safe to because my tank is full of fast growing plants. In your tank your fish will be fine, but i would dose normally day 1&2, 2x day 3&4, 3x days 4&5