Going insane, blue green algae.

[Joseph Elliott]

My tank is infected with cyanobacteria and i dont know how to kill it. been doing water changes every other day and it not helping. Found a few sites online that suggest eryithromyacin as a antibacterial but its a whooping cough prescripiton and ive never had it. any ideas?

[Baos]

API makes it. It's generally prescribed for people who can't take penicillin

[werner]

A couple years back, I had a massive outbreak of that gunk. You should be able to get rid of it without antibiotics, but it takes a little work. Antibiotics should be an absolute last resort since they will also nuke your good bacteria and mess everything up.

#1- Remove as much of the stuff as you can manually. Get every last bit of it! Then let everything settle and vacuum any specks off the bottom or else they'll start growing again.

#2- Increase water movement in the tank. Cyanobacteria does not like well oxygenated water. Add a small pump or powerhead if there are dead spots in the tank.

#3- Decrease the photoperiod to 10 hours or less. Even turning the lights off an hour earlier can help knock it back.

#4- Add a whole bunch of fast growing stem plants. Healthy plants have antibiotic properties.

#5- Make sure there are enough nitrates (10-20ppm). Cyanobacteria often appears in tanks with low nitrate levels since it can use atmospheric nitrogen. Also make sure that other ferts and CO₂ are high enough for the plants to take advantage of.

#6- The Secret Weapon: hydrogen peroxide! Get a small syringe and shoot this directly on any spots of BGA that might reappear. Don't go crazy since this can also damage your fishes' gills and nitrifying bacteria if used in high enough concentrations.

Some great info on cyanobacteria here: The Skeptical Aquarist and here: Aquarium Algae (bottom of the page.)

[Joseph Elliott]

Thank you very much, hopefully i can irradicate this crap with this info.

[jvision]

A 4-day black-out will kill it all. Your plants and fish will be fine.

Do a 50% WC, and if you're dosing CO2, turn it off. Also, if you're dosing ferts, dose KNO3 only. Black out for 4 days, then do another 50% WC. Turn CO2 back on and dose ferts regularly.

Edited February 19, 2009 by jvision

[Parachromis1]

When I had a cyanobacteria outbreak, I did just as Jay stated. I blacked out my tank and didn't feed for nearly a week. I also added quite a few airstones to oxygenate the water.

[devocole]

I've blacked it out once before, it seemed to work okay.

I usually just use maracyn for a few days and never see the stuff again. I've never had fish deaths. All the other methods are such a pain.

[werner]

Blackout?!?!?! Don't tell me it's that simple- that was about the only thing I didn't try when I had it... :shock:

[firestorm]

I read on aquarium algae blogspot that the blackout period is supposed to work for this bacteria. Clean up as much as you can from the tank first, add lot's of airstones since the dying bacteria will decrease oxygen levels, and cover the tank from top to bottom in garbage bags or something. After the 4 days remove the bags, clean the tank again and see if it killed it all, if not I would cover it back up and do it again. Fish can easily go a week without food, so don't worry about them too much.