Cyanobacteria In Planted Tank

[Katty]

I have a 20 gallon planted tank that has been having a lot of trouble with what appears to be cyanobacteria. It's a deep green color and sort of makes thick webby sheets over the top of gravel, plants, etc. that slough off when touched. When there is a lot of it in the tank it has a very strong pond smell.

I do weekly ~4 gallon water changes and remove as much of the algae I can when cleaning but it's difficult to get every little bit, and it has been spreading faster and faster each week. It started off in one corner on the gravel but has moved to the other side of the tank and is now trying to smother the rotala, which is almost impossible to get it off the tiny delicate leaves.

I tried reducing the light time by about an hour but I feel like it's only gotten worse since then.

What do I do?

 

[thereverendturtle]

Ironically, cutting back on light, benefits cyanobacteria. Some people may disagree, but red slime remover marketed for salt water aquariums, works just as well in fresh water. I've used it successfully in the past without any adverse affects.
Other things you may want to try first would be, replacing your light bulbs if they are more than a year or so old. Increasing water flow also helps. Check your nitrate and phosphate levels they may be really high which can fuel its growth.

 

[SO19Firearms]

http://www.theplantedtank.co.uk/algae.htm

Description
This isn't a true algae, but a bacteria called cyanobacteria that is able to photosynthesise. Covers everything in a blue/green slimy mat. Easily peels off but grows back again very quickly. It can smell pretty foul. It is very commonly found in the substrate and especially along the front glass where is receives light.
Cause
Often caused by very low nitrates. It is fairly common to have it growing in the substrate against the front glass from where it can spread. Sometimes it appears with new setups that have had light and ammonia present at some point. Dirty substrates and filters may also bring it on. Poor water circulation is another possible cause.
Removal
A blackout is the best method for this. Clean out as much of the algae as you can and do a 30 to 50% water change. If your nitrates are low then add some potassium nitrate to get levels to 20ppm. Remove CO2 and add an airstone. Turn off lights and cover the whole tank so no light can enter. Leave it for 3 to 4 days. No peeking and no feeding - fish will be fine without food for this period. After 3 to 4 days remove the covers and do a 30 - 50% water change. Remove airstone and start CO2. You will need to dose nitrates to keep them dropping too low again. Make sure your substrate and filter doesn't become too clogged up with mulm and also make sure you have good water circulation around the whole tank.
Another option is to treat with Maracyn which is an anti-biotic. Seems to work well but may affect the biological filter. In the UK it is illegal to purchase Maracyn without first getting a prescription for it from a vet.
If the BGA is originating from the substrate place some dark tape on the glass to hide the substrate from direct light.

Check your nitrate and phosphate levels they may be really high which can fuel its growth.

Nah.

 

[aaronnorth]

Other things you may want to try first would be, replacing your light bulbs if they are more than a year or so old

No need to do this either,
Aaron

 

[Katty]

So is a blackout the best solution?

 

[ian]

yes a blackout is the best method...light is the driving force behind any algae and without light, the BGA cannot survive. BDA also thrives on low N03, so my advice would be to do a massive water change, add some extra N03, add a powerhead to help circulation and the blackout for 3-4 days (no peeking).

 

[njw1383]

Dose the tank with a 3% hydrogen peroxide solution at a rate of 1ml per gallon. By the next day all your cyanobacteria will be gone! It works AMAZINGLY WELL!!

http/www.youtube.com/watch?v=Rm7aPcCsuOw

 

[snowflake311]

Killing it will not cure it. You have to find the cause of the algea. If you kill it off but don't change anything it will come back.

I had this nasty blue gree slime get the best of me. I gave up and let it take over. Then one day I was over it. I took the whole tank apart. Replaced the substrate added better water movement. I raised my light up 4 inches from the surface to lessen the light intensity. I shortened the amount of time the light was on. I also added lots of plants. There were a few spots that showed up even after redoing the tank. But with the adjustments I made it dided off and has not come back. I was slacking of WC and cleaning the filter.

I think my filter being extremely dirty for a long time was the main cause of this stuff getting out of control. With a few little adjustments and clean the tank with a well cleaned filter you will get rid of it. Fix the problem

When was the last time you cleaned or rinsed out your filter? What's the water flow like? Do you have any surface movement? Low o2 can be a cause. How often do you do WC and how much?