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Discussion Starter · #1 ·
Hello everyone

I’m new here - so hello - pleased to e-meet you!

I’m aware its kind of rude to instantly come up with a question, but I’m having sudden algae growth in my 34l fluval flex tank, so I would really appreciate some help :)
The tank is planted, I add CO2 and I have the lights on for 8hrs a day. I exchange about 30% of the water once a week.
The inmates are an oto, a few amanos, red cherries (3), 2 snails and 5 tetras. All was going and growing well until recently, when these ugly algae started appearing. First on the moss, now on most of the plants.
I’m not sure what kind of algae it is - so I attached photos. Would be great if someone could help me identify it.

Thanks a lot
 

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Welcome to the Planted Tank!

Algae can sure be a nuisance. The exact name/type often doesn't really help much. Could be hair, brush/beard or even staghorn algae.
The real question is, how to kill!! :)

There are a few different scenarios, what I have seen happening most frequently is that a relatively new tank runs out of nutrients, plant grow stalls, and that is when algae come into the picture.

As you know, to grow, plants need lights and nutrients. Looks like you got enough light and CO2.
So, my first question would be - what do you add in terms of macro (NPK) and micro nutrients?

A different scenario could be that this is a new tank that hasn't found its balance yet, and is experiencing the initial cycles of alga growth. In that case, keep doing what you are doing (helping plants to grow really well) and be patient for a few weeks. Often those algae explosions blow themselves out without much help or scrubbing.
 

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Discussion Starter · #3 ·
Thanks a lot for your reply!

Agree - name doesn't matter :)
This hairy kind of algae is especially annoying since physical removal is almost impossible. Especially from the moss ...

I'm adding 1 pump of "Tropica Premium Nutrition" once a week after the water change.

I've set up this tank about 2-3 months ago.

What I forgot to mention in my original post - and it may not be important anyhow, I'm also chilling the water to keep it at around 26 degrees Celsius. (I'm living in Singapore and without chilling or having the aircon on nonstop, the water temperature quickly raises above 30)
 

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So it sounds like your tank may be out of Nitrates (and perhaps Phosphates, depends on your tap water).
Macro nutrients - Nitrates, Phosphates, Potassium - are needed for plant growth. If you don't add them one way or another, after an initial charge they run out, plant growth stagnates, and algae moves in.

I use KNO3, K2SO4, and KH2PO4 to dose these three (small amounts, but essential).
The fact that you add CO2 without adding macros invariably leads to algae hell. >:)

So, see if you can source any of that (KNO3 may be problematic), and read up on dosing.
 

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Discussion Starter · #5 ·
Thats interesting! The only one of the 3 you mentioned I'm regularly monitoring is NO3 - and its usually around 15-20ppm. I was of the opinion that its rather important to avoid too high levels. PO4 I thought about that same ... and also that both are a byproduct of having fish in the tank.
Potassium is a different story. - Started adding it now :)
 

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It is true that "fish are fertilizer" to some extent. But, this can lead to issues. Most reasonably stocked tanks with lots of fast growing plants tend to run out of NO3 fairly quickly. So I am a bit surprised you are reporting 15-20ppm, that is pretty much optimal if true.
If you have large poopers which keep the NO3 levels up this may lead to other issues, like biofilm accumulating on leaves and choking plants over time.
So I would say it is not a good approach to try to balance fish excrement with plant nutrition. Regular water changes with a bit of nutrient dosing go a long way towards a balanced, healthy planted tank...
 
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