Eliminating Cyanobacteria Causes

Phil Brosso
  • #1
Hello! I'm not sure I'm posting this in the right thread since cyanobacteria are not algae, but here I go.

I have a 1 year old 65 gallon aquarium with low live stock:

10 harlequin rasbora

6 nerite snails

1 rabbit snail

A few malasian trumpet snails (to mix my sand substrate)

5 amano shrimps

And quite a few live plants (see pictures)

I have a eheim pro 2 canister filter, in-line CO2 at around 30 bubbles per minute and water is at 78 degrees. I do 30% water changes once a week.

Right now, I have 0 algae and my water parameters are fine. The cyanobacteria is only on driftwood. It will sometimes get on plants, but there's none on the substrates or fake rocks.

This is what I tried, not necessarily in order since I don't exactly remember the exact order:

Playing with lighting: I have tried to augment and lower lighting. Right now, I have CFL 6500k 23w bulbs distributed left and right. I have tried different configuration, numbers (From 1 to 6 bulbs) and locations. I changed the bulbs very recently too. Again, I don’t have algae. I’m presently working on led lighting with 6500k, 10000k, red and blue bulbs so that’s my next step for lighting.

Improving flow : I added a water pump not long ago to improve surface agitation. Right now, I leave about a cm out of the water to pull air and improve water oxygenation.

Reducing fertilizer : I was dosing seachem flourish and iron. I tried putting more, less and none at all. I didn’t see any changes.

Reducing temperature : I read that cyanobacteria grows slower in cooler temperature, so I gradually dropped from 80 to 78, but I don't really want to go lower for now.

Adding nitrogen : I heard that cyanobacteria might emerge with a lack of nitrogen in planted tanks. I dosed seach flourish nitrogen at the recommended dose. Didn’t see a change there either, though this is my most recent try.

Removing it by hand : I try to remove as much as I can, but it’s very thin and doesn’t carpet like it’s supposed to.

What I didn’t try : peroxide, antibiotics, alcohol/vinegar, uv sterilisation.

Any clue or ideas for what I should try?



(Yes, there's a lot of floating particles, I had just cleaned up and made a water change.)
  • #2
Lol, good eye, I think it is cyanobacteria too cause it is more blue than green... get it, CYAN

Anyway, cyanobacteria can use nitrogen gas if it is FAVOURABLE. Meaning, if it is worth doing. The 'worth doing' is based on which species it is though.
Nitrogen gas comes from Nitrate (NO3->N2). Seeing that you water parameters are "fine", I am not sure if nitrogen is causing your cyano bloom. If anything, taking away as much nitrogen gas as possible would prevent its proliferation, i.e., adding plants to keep nitrogen from floating around and agitating the soil/driftwood to release the gas.
Only add nitrogens if you system is lacking it.

Another thing they need is CO2, soooo, only add what is lacking as well.

University knowledge, though, lol, I haven't experienced a cyano bloom yet
  • #3
It's too much light. I get a patch of it exactly where the sunlight comes in.
Phil Brosso
  • Thread Starter
  • #4
I get a feeling it's light too, that's why I'm switching to a better distributed LED system with reds and blues. The left side is covered by duckweed and taller plants and has 0 cyanobacteria patches.
Phil Brosso
  • Thread Starter
  • #5
Update! I went for a more extreme measure to fight off my cyanobacteria patches. Right now, only one element was affected by cyanobacteria patches : my driftwood! So my solution was getting it all out of the tank, including my huge piece of log. It included a lot of plant moving and rescaping, but I'm now free of cyanobacteria. For now.

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