Blackbeard algae in main tank! Need help.

Ozzie Boss

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Sep 28, 2018
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Hello it’s been a while. I have been fighting a algae problem and with my plants in general. Based on the photos I think I have early Blackbeard or hair algae and green spot algae on my plants. The plants themselves also aren’t in good condition either. The bacopa has holes in certain leaves I can’t be sure, but I think it was the rubber lip pleco I had in there. Problem started when I put him in there. The cypts look melted and full of backbeard as does the vallisneria. I have target dosed excel and it seems to be killing the Blackbeard but without eliminating the problem I think it will just grow back. Does anyone know what caused Blackbeard or how to treat it?

Tank details

Lighting: Beamswork LED 9 hours of lighting a day

Fertilizer: 5 pumps of easy green every week or water change.

Tank size: 50 gallons.

Plants: Bacopa, Anubias, vallisneria, and Crypts.

Water Parameters:
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: Around 10
Ph: 7.8



Feb 25, 2009
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"Problem" algae like black brush/beard algae (which is what is on the plants in the photos) is caused when there are nutrients in the water and light is present. In other words, it is completely natural. As to why one species of algae may appear in one tank and a different species in another when they have very similar biological systems I do not know; Karen Randall [I think, going from memory] used to mention this in her monthly columns, how different algae would take over in different tanks under similar conditions.

When you have plants, you want the algae to be under control. There is only one way to do this, by establishing or restoring the balance of light/nutrients in the aquarium. Nothing else will work because nothing else deals with/corrects the cause.

Here I will digress for a moment, on the Excel. This should never be used in an aquarium with fish. It contains glutaraldehyde, a highly toxic disinfectant. The fact that it often kills Vallisneria even at recommended doses, and will kill this algae (sometimes anyway), tells us it has no place in a fish tank. Enough on that.

Light is the single most important part of the balance. Intensity and spectrum are factors, and then duration. The intensity must bee sufficient to drive photosynthesis in each plant species (they vary), then it must be the right colour (red and blue drive photosynthesis, red the more crucial, and adding green does improve plant growth). Once these two criteria are met, the duration can be twigged to discourage algae.

Once the light is what you need, nutrients can be added to supplement those already present naturally.

I have battled this algae over the years, and even did some tests which determined that this algae could be encouraged by the light being too bright, or too dim, or on for too long each day. I also had it appear with excessive fertilization. I also found that the increased daylight entering the fish room in summer months could cause it. But once you have the balance, end of problem algae. It will still be there, it is after all natural, but it will be under control and not increase.