Blue-green algae

[Delapool]

Hello, I have 125g freshwater tropical tank with community fish/ live-bearers and plants. I had blue-green algae clumps and ended up taking the rocks out and cleaning. I read that a ph slightly below 7 discourage's it and wondered if this was true if anyone may know? My fish are healthy, water parameters good (ph about 7.5) and plants do ok when not being eaten. Normal green algae is pretty minor in the tank. Thanks in advance.

 

[Rivercats]

Are you talking about blue-green algae that is actually cyanobacteria? The one thing that can often help but is still no guarantee you won't get it is to keep your nitrates over 10ppm. When nitrates are lower than that cyanobacteria is more likely to appear in your tank.

 

[aqua_chem]

In addition to nitrates, it's also potentially caused by too much light, low flow, or poor tank hygiene. There are a lot of things that can cause it.


As far as getting rid of it, using an antibiotic is by far the best way to deal with it, but it can be expensive in some circumstance, and some people dislike using antibiotics for a variety of reasons (afraid of bb damage, antibiotic immunity, etc). If this is the case, you can try spot treating with h2o2, which I have decent luck with in more confined cases, such as if you have only a few patches of it.

 

[Delapool]

Many thanks for the advice. Yes, it is the cyanobacteria I believe (I tried an algae cure anyway with no luck). The nitrates have dropped down to about that level and would make sense on the timing as well. Very interesting! I cleaned the rocks as it has been slowly spreading out (annoying as I had one patch for a long time and should have got onto it straight away), but I think I could spot treat quite well – I’ll chase up the h2o2 at the chemist. Thanks again.

 

[Rivercats]

You will want to get Hydrogen Peroxide 3% solution. You can use 1 to 3ml of Peroxide per 1 gallon of tank water. Turn your filters off and pull the proper amount of Peroxide for the size of your tank in a syringe and slowly squirt the Cyano as close to it as possible. Leave the filter off for 20 minutes. You can do this once a day. I would vacuum up as much of the cyano as possible then spot treat what is left.

 

[Delapool]

I've picked up the Hydrogen Peroxide and will try this on the weekend. Does it take a few days to kill it off and is there any way to tell when it is dead?

 

[aqua_chem]

If its bubbling, it's hurting. By the next day you should be able to tell that it's not doing well at all.

 

[Delapool]

Grand! Many thanks.

 

[FrankAbagnale]

I would suggest reading this article: http://www.aquariumalgae.blogspot.com/

I think the suggestion so far is a good remedy for now, but doesn't really fix the overall problem. I would focus more on plant health and balancing the light, nutrients, and co2.

 

[Delapool]

Hi, The photos didn't work out so well but I did see bubbling and it looks more patchy then before. Also thanks for the link - I'm spending heaps more time with the tank set-up (when I thought it would be the fish) so that was handy.