Green Algae

[kate28]

Hi, I'm new here & hoping someone can help with my problem. My 300 liter cold water tank started getting a vigorous algae problem about 2months ago, its a very dark green algae- almost forest green and looks like a thick layer of moss, mainly on the tank floor but is now covering the plants, wall and filter attachments. I have been siphoning it out regularly which helps for 2-3 days then its covered again. I've tried turning the lights off which has helped a little bit but not much. I added a heater on low which also helped a little but again not enough. I have read algae growth indicates a healthy tank but in the last two months 2 fish have died & also read chemical algae killer is pretty bad for the fish. Is that all correct?

I've just bought an 80L temporary tank so I can shut the big one down & start from scratch when the problem is sorted. What is the best way to ensure it wont come back?

[blueether]

It sounds like cyanobacteria aka blue green algae and is not an algae but a bacteria.

It tends to do well in high phosphate conditions and often in low flow areas.

What food do you feed, and how much?

Are you keeping goldfish?

How often are you changing water, and how much do you change? Do you clean the filter at the same time and how do you clean it?

Do you have many plants?

cyano is in nearly all tanks, just some times it will run rampent...

[kate28]

I have just google imaged that and yes it looks exactly like Cyanobacteria. I am keeping goldfish but now only have 3 left. They get fed nutrafin flakes every second day and bloodworms once or twice a week. I try to take a bit of water out each fortnight, probably about a third. I don't normally clean the filter but a while ago I took out all the filter wool and started fresh. I used to have heaps of plants but since the algae has taken over most have died and the fish also ate/destroyed some, the few that are left are absolutely covered in it.

Should I empty it and completely start again by cycling it? What is the best way to clean the substrate(stones) and everything else?

[blueether]

I wouldn't strip it down just yet.

I would increase the w/c to 1/3 a week, or more often, and gravel vac the stones well each time, goldfish can be messy eaters/poop machines.

[Adrienne]

As said Cyano is a bacteria and normally forms in places where there is virtually no water movement. There are treatments available to get rid of it but regular (at least once weekly 30% water changes) combined with good vacuuming to remove it all each time should reduce it a lot. Increase the water flow in the tank. It is a green/blue algae and forms like a sheet of gladwrap on the surfaces.

Treatments which work are

cleaning as above

furan 2 (available from lfs)

erythromycin (script only from a vet), it is an antibiotic so can mess with your filter bacteria

and there is also a green-blue algae remover available from HFF (Mt Roskill) and probably other shops, targeted specifically at cyanobacteria but the actual name eludes me at the moment.

[amtiskaw]

I've had good results with a three day blackout. Remove as much BGA as you can manually, then totally cover the tank so no light gets to it (I use the garden rubbish sacks from the supermarket) and leave it for three days. No peeking! Then give it a good vac/water change.

Repeat a week later if there's still traces of BGA.

I tried the BGA remover from HFF, but it only reduced the BGA rather than removing it.

Long term, the cyano may come back, and you'll need to address the underlying cause (I agree with blueether on causes)

[F15hguy]

you could always go see a vet and ask for a prescription for erythromycin, kills it but is expensive.

best to sort out the causes first and use it once your sure you can prevent it coming back

easier than pulling apart your tank