Bright Green Algae that keeps coming back...

Hi All,
I have a 20 gall freshwater tank, it's got 7 Harlequin Rasboras, 1 Betta, and 5 Sterbai Corys. Ive had it for 3 months or so. I do PWCs every week, now about 25% or so, and tested the water weekly for the first 2 months, and levels have been all ok every time I tested them the first two months.
I feed 1 or 2 x's a day, so not too much.
In the last 4-5 weeks theres a bright green algae that forms on the walls, rocks, plant surfaces, and substrate surface. It scrubs off easily, but now is coming back only 3-4 days after my PWC.
Any ideas as to why its happening and what I could do?
Thanks for the help,
Damon

 

Do you still test the water? I'd test it and get some current numbers, and post those here. Sometimes "ok" may not be enough to determine the issue.

That looks like Cyanobacteria to me, not algae. It'll usually be caused by lots of excess nutrients and not much flow, but it'll take hold in a lot of tanks without too much of a reason.

I recommend Erythromycin - it's an antibiotic that won't have an impact on your cycle but should take care of the cyano. You can also use chemiclean, and that should work too.

I would probably feed once a day, and lighten up on the amount for now. Siphon out the cyano, treat with Erythromycin/Chemiclean, and try and keep nitrates low. That should get rid of it and keep it gone. Sometimes adding some fast-growing live plants will also help keep it from coming back, since the plants will be consuming some of the available nutrients that likely caused the issue in the first place. It can be tough to grow healthy plants with an active cyano infection, so adding the plants after you've treated the tank will probably be best.

 

I am thinking what you are seeing isn't actually algae. It is cyanobacteria (often called blue green algae) Get some UltraLife Blue-Green Slime stain remover. Follow directions for dosing it 2 times and the stuff should be gone.

 

Source?

it's an antibiotic that won't have an impact on your cycle

I have only ever read that this will also kill your bb.
Erythromycin:
Erythromycin is a antibiotic very similar to Penicillin. It is more effective in freshwater aquariums than in saltwater but can be used to treat difficult eye problems. Some aquarists also recommend Erythromycin to treat cyanobacteria blooms but this should be used with caution and the cause of the cyanobacteria still needs to be addressed. While Erythromycin is useful with especially gram-positive bacterial infections, it can also kill the usefully nitrifying bacteria in the tank and may cause some instability while the helpful bacteria population recovers. Avoid using this medication if the bacteria population is already unstable, like in new or newly established aquariums.

 

Thank you all for the insights. Regarding the nitrate levels, if high, how do you reduce them?

 

Thank you all for the insights. Regarding the nitrate levels, if high, how do you reduce them?

Water changes

 

Thank you all for the insights. Regarding the nitrate levels, if high, how do you reduce them?

Water changes. Bigger ones if you are not now. At least 50%.

 

Do 50% weekly water changes. Small volume water changes don’t do much. It can help to know the nitrate level coming from your water source e.g. tap or well.

 

Source?

I have only ever read that this will also kill your bb.
Erythromycin:
Erythromycin is a antibiotic very similar to Penicillin. It is more effective in freshwater aquariums than in saltwater but can be used to treat difficult eye problems. Some aquarists also recommend Erythromycin to treat cyanobacteria blooms but this should be used with caution and the cause of the cyanobacteria still needs to be addressed. While Erythromycin is useful with especially gram-positive bacterial infections, it can also kill the usefully nitrifying bacteria in the tank and may cause some instability while the helpful bacteria population recovers. Avoid using this medication if the bacteria population is already unstable, like in new or newly established aquariums.

I've used it in many, many cycled tanks to treat a variety of conditions without issue and have seen others do so as well. I'm sure in high dosages it would absolutely have a negative effect on BB, but I've had no issues following the instructions on the package.

Here's some good discussion:
https://www.cichlid-forum.com/phpBB/viewtopic.php?t=238445

API recommends the addition of Quick Start (of course it's their product, but bacteria nonetheless) while using Erythromycin under the "Faqs" section:
API® | E.M. ERYTHROMYCIN™

Here, Cory talks about using Maracyn (Erythromycin) to cure Cyano:

There doesn't seem to be much in the way of actual studies done on the effects of Erythromycin on Nitrifying bacteria, but I can confidently say that in all my time using it, I've never had any issues with it.

Sorry, OP - don't mean to de-rail. This may be best to discuss in a separate thread, if there needs to be more discussion

 

I've used it in many, many cycled tanks to treat a variety of conditions without issue and have seen others do so as well. I'm sure in high dosages it would absolutely have a negative effect on BB, but I've had no issues following the instructions on the package.

Here's some good discussion:
Medications which affect Beneficial Bacteria

API recommends the addition of Quick Start (of course it's their product, but bacteria nonetheless) while using Erythromycin under the "Faqs" section:
API® | E.M. ERYTHROMYCIN™

Here, talks about using Maracyn (Erythromycin) to cure Cyano:

There doesn't seem to be much in the way of actual studies done on the effects of Erythromycin on Nitrifying bacteria, but I can confidently say that in all my time using it, I've never had any issues with it.

Sorry, OP - don't mean to de-rail. This may be best to discuss in a separate thread, if there needs to be more discussion

I have used it in the past also and it killed my cycle and then it came back again in a few months. I think it depends on how experienced the aquarist is and also and how established the tank is.

 

Looks to be cyano. Read before this is caused by high phosphates?

Cleaning filters and adding prolific feeding plants are a big help in the nitrate reducing too.

Getting a ton of floating plants in there might be worth a shot!

 

Thanks everyone!
What are some types of feeding plants worth adding in there?

 

Thanks everyone!
What are some types of feeding plants worth adding in there?

If you're talking about fast-growers, Anacharis, Hornwort, Pothos, Red Root Floaters, Duckweed, etc... Most stem and floating plants will use up a lot of nutrients.

I'll stand by that you should treat first, then add plants. IME, Cyano will cover plants and smother them, causing them to rot and release even more nutrients into the water. Chemiclean should be a good, cheap product to track down to treat with.

 

Got it, thank you.

 

Sorry to walk in like this, but I'm having the same issue I wanted to ask, are these remedies safe for shrimp and pond snails?

 

Sorry to walk in like this, but I'm having the same issue I wanted to ask, are these remedies safe for shrimp and pond snails?

I have a shrimp tank that had this problem. It has some snails as well. I treated with chemiclean and had no losses at all. One treatment cycle took all of the cyano out and left my tank looking great. Just be sure to follow the directions exactly how they say on the packaging.

 

BGA (not actually an algae) is extremely hard to stop from coming back without intervention. The biggest factors are low flow COMBINED with light. Nitrates alone will not cause it, only contribute to it when combined with low flow and light.

It also loves sunlight. Low flow + light = BGA, nutrients or not…or measurable nutrients. It needs very little to feed, any tank would have a enough. Nutrients will only fuel it not cause it, of course the more nutrients the more fuel, meaning bigger problem. I use to battle it all the time because the sides of my substrate get nailed with sun.

There is really no way to get flow into compacting soil substrate so I still battle it every now and then but I use the ultralife every 3-4 months (without it, it grows back in a week). The day I add in the second dose per directions (day 3), I clean sides of substrate and let the water containing ultralife get in around the sides. Keeps it clear for several months until it eventually dissipates.

The antibiotics will work but will affect fish more. I have never used chemiclean.

One speck of BGA can bloom very rapidly so it’s important to manually remove every bit of it you can, which is much easier after treatment when it starts to break up…though it’s pretty easy to remove anyways.

With that amount I’d wear gloves, maybe even a mask. You do not want a large amount of this stuff getting into an orifice, or around a pet. We usually don’t deal with large enough amounts to be too concerned but just to be one the safe side.

Once fully eradicated I’d look into a power head, adjust lights and it should not come back. However mine does because unfortunately we have it in the water source.

 

Ugh cyanobacteria......

 

Ugh cyanobacteria......

thankfully it is one of the easier things to get a handle on.