Cyanobacteria with ultra low nutrients

[Gaoweihd]

hi, my tank is 4 month old and over the last four weeks, NO3 is always 0 and PO4 is 0.02 from Hanna. However, the red slime Cyanobacteria has been spreading from rocks to rocks.

flow should be ok. Can anyone help to take a look if it’s really cyano and what’s the best way to deal with them?( I’ve searched a lot, most post says high nutrients and low flow are the cause, but that’s not in my case)

 

[CHSUB]

Imo, yes Cyano. I had a small issue in December with very similar nutrient levels. Manual removal helped and now it is completely gone without much effort besides normal maintenance. I run GAC and do weekly WC with an effort to remove detritus.

 

[JTP424]

I'd also be curious about how much daylight the tank gets, from the photos it looks like there is some. While it isn't typically a cause of cyano, it can definitely strengthen its hold.

 

[Gaoweihd]

Imo, yes Cyano. I had a small issue in December with very similar nutrient levels. Manual removal helped and now it is completely gone without much effort besides normal maintenance. I run GAC and do weekly WC with an effort to remove detritus.

how old is your tank? Thanks for sharing , I’ll start to suck debris during my weekly water change

 

[Gaoweihd]

I'd also be curious about how much daylight the tank gets, from the photos it looks like there is some. While it isn't typically a cause of cyano, it can definitely strengthen its hold.

The tank is sitting beside a window facing east, during a sunny day it get about 4 hours of direct sunlight. I really like those hours that fish looks super colorful under the sunlight

 

[Lasse]

most post says high nutrients and low flow are the cause, but that’s not in my case

IMO - you have read post from the past. In my world Cyanobacteria and dinoflagellate blooms in a newly started aquaria is mostly caused by too low nutrients not too high. I would rise the NO2 to above 2 mg/L and the PO4 to around 0.06-0.1 mg/L. I would also stirr around the mats every evening before light gets out.

In your last picture - you show a perfect picture of a cyanobacteria mat - IMO- The cells is the sticks and the read around them is external stored sugar from the photosynthesis. When you stirr around the jelly-like shell, you deprive the cells of their external energy store of organic carbon (in the form of sugar). They have a harder time growing and multiplying without it. You don't have to worry about spreading cells everywhere because the water already contains enough cells, but what likely triggers the mat formation is that there is likely organic N and P where the mats have been formed.

The low nutrient levels hinder "good" algae and bacteria to form a biofilm that make it more difficult for the cyanobacteria to settle down and form mats.

You can get cyanobacteria blooms with higher nutrients too - I have it - but IME - this happens mostly in old and mature tanks and are caused of other imbalances.

Sincerely Lasse

 

[Gaoweihd]

IMO - you have read post from the past. In my world Cyanobacteria and dinoflagellate blooms in a newly started aquaria is mostly caused by too low nutrients not too high. I would rise the NO2 to above 2 mg/L and the PO4 to around 0.06-0.1 mg/L. I would also stirr around the mats every evening before light gets out.

In your last picture - you show a perfect picture of a cyanobacteria mat - IMO- The cells is the sticks and the read around them is external stored sugar from the photosynthesis. When you stirr around the jelly-like shell, you deprive the cells of their external energy store of organic carbon (in the form of sugar). They have a harder time growing and multiplying without it. You don't have to worry about spreading cells everywhere because the water already contains enough cells, but what likely triggers the mat formation is that there is likely organic N and P where the mats have been formed.

The low nutrient levels hinder "good" algae and bacteria to form a biofilm that make it more difficult for the cyanobacteria to settle down and form mats.

You can get cyanobacteria blooms with higher nutrients too - I have it - but IME - this happens mostly in old and mature tanks and are caused of other imbalances.

Sincerely Lasse

Thanks for the detailed tips. I'll try your method. I've been feeding a lot of pellets and reef roids twice a week, but my NO3 is always 0. I've turned off the protein skimmer and will see if the skimmer is too powerful, will test NO3 again on Saturday. If it's still too low, I guess the auto roller filter out too much stuff and I'll probably stop using it for a while

 

[CHSUB]

how old is your tank? Thanks for sharing , I’ll start to suck debris during my weekly water change

My tank hits 1 year this month and Cyano appeared after ~6 months and peaked maybe around 8 and is completely gone now. Imo, nutrient are not an issue, Cyano is everywhere, always and first. Manual removal, limited real estate, and time are the best actions, imo,

 

[slingfox]

Thanks for the detailed tips. I'll try your method. I've been feeding a lot of pellets and reef roids twice a week, but my NO3 is always 0. I've turned off the protein skimmer and will see if the skimmer is too powerful, will test NO3 again on Saturday. If it's still too low, I guess the auto roller filter out too much stuff and I'll probably stop using it for a while

Do you only feed your fish twice a week in total? You probably should feed them daily.

 

[CHSUB]

protein skimmer and will see if the skimmer is too powerful, will test NO3 again on Saturday. If it's still too low, I guess the auto roller filter out too much stuff and I'll probably stop using it for a while

This is exactly opposite for success. Cyano feeds on the stuff that these things remove…

 

[Ancient Mariner]

And the debate continues! High nutrients, low nutrients, low flow, low light, etc., etc. I’d say no one knows why. I had a little spot of cyano in December 2024. At that time nitrates were 50 mg/l. I changed nothing and I just observed the outbreak and did not clean up or siphon the area to see what happens. It took 4 months but now it is completely gone. Same light. Same flow. My nitrates are now <.05 mg/l (for various reasons and not in response to the outbreak). Go figure.
https://www.reef2reef.com/threads/why-does-cyano-grow-here…and-only-here.1087149/

 

[Ancient Mariner]

My tank hits 1 year this month and Cyano appeared after ~6 months and peaked maybe around 8 and is completely gone now. Imo, nutrient are not an issue, Cyano is everywhere, always and first. Manual removal, limited real estate, and time are the best actions, imo,

Totally agree!!!

 

[CHSUB]

And the debate continues! High nutrients, low nutrients, low flow, low light, etc., etc. I’d say no one knows why. I had a little spot of cyano in December 2024. At that time nitrates were 50 mg/l. I changed nothing and I just observed the outbreak and did not clean up or siphon the area to see what happens. It took 4 months but now it is completely gone. Same light. Same flow. My nitrates are now <.05 mg/l (for various reasons and not in response to the outbreak). Go figure.
https://www.reef2reef.com/threads/why-does-cyano-grow-here…and-only-here.1087149/

Yes, so true. I had Cyano grow on an mp60 at full power…

 

[Lasse]

NO3 can be difficult to rise with food and my opinion is that lack of NO3 as a molecule has more dimensions in the mats formation than just be a nutrient. It will take a short novel to explain that - I only just say that I prefer to add NO3 in the form of NaNO3 (Chile saltpeter) in a newly started aquarium. You probably can find it at the spice shelf in your grocery store or on Amazon.

40 gr of NaNO3 in 500 ml of RO water will give you a stock solution. 1 ml of this stock solution to 100 L of water will rise the NO3 concentration with around 0.5 mg/L (ppm)

I you feed with reef roids you will get some PO4 into the water - IME. If you want more feed reef roids more often. However - in a newly started aquarium - especially if it has been started with mainly dry and "dead" stones - your stones and other decor is low in bounded PO4. It means that they will "suck" up some and you sooner or later get a ketchup effect - 0, 0, 0 and suddenly upp near the roof.

When discussing low or high levels of NO3 causing cyanobacteria mat formation - IME - you have to take the age of the aquarium into account when deciding on tactics. With 0 NO3 in a newly started aquaria and cyanobacteria mats - I would rise the NO3 all days in the week as the first action combined with daily disturbance of cyanobacteria mats when they are at their largest

Sincerely Lasse

 

[CHSUB]

NO3 can be difficult to rise with food and my opinion is that lack of NO3 as a molecule has more dimensions in the mats formation than just be a nutrient. It will take a short novel to explain that - I only just say that I prefer to add NO3 in the form of NaNO3 (Chile saltpeter) in a newly started aquarium. You probably can find it at the spice shelf in your grocery store or on Amazon.

40 gr of NaNO3 in 500 ml of RO water will give you a stock solution. 1 ml of this stock solution to 100 L of water will rise the NO3 concentration with around 0.5 mg/L (ppm)

I you feed with reef roids you will get some PO4 into the water - IME. If you want more feed reef roids more often. However - in a newly started aquarium - especially if it has been started with mainly dry and "dead" stones - your stones and other decor is low in bounded PO4. It means that they will "suck" up some and you sooner or later get a ketchup effect - 0, 0, 0 and suddenly upp near the roof.

When discussing low or high levels of NO3 causing cyanobacteria mat formation - IME - you have to take the age of the aquarium into account when deciding on tactics. With 0 NO3 in a newly started aquaria and cyanobacteria mats - I would rise the NO3 all days in the week as the first action combined with daily disturbance of cyanobacteria mats when they are at their largest

Sincerely Lasse

I have had Cyano appear in every aquarium, including FW haha, with no pattern or reason why? I have found only one solution that imo is 100% effective. Manual removal with a canister type filter EVERYTIME it appears and after a few weeks and several cleanings it’s gone.

 

[Lasse]

If so - we have different experience - the way I have done in every new aquarium I have started that get cyanobacteria mats is to add 2 mg/L NaNO3 and stirr the mats every evening. A couple of years ago I start to add 2 mg/L NaNO3 already in the beginning (or used a lot of old water with NO3 in it). Never have had cyanobacteria mats in any new aquarium since I start to use NO3 already from the beginning. You will have cyanobacteria in every aquarium but the forming of the mats is another question. It happens of some reasons and in a new started aquaria with low or no inorganic nutrients they will have an advantage in the fight for space because they can apparently assimilate organically bound nutrients as well - something that ordinary algae cannot do (with a possible exception of some dinoflagellates). Nutrients in the water column will evens out the fight for space. If you then help by removing their energy stores, it will improve the situation for the "beneficial" algae and bacteria

This implies that organic carbon should not be added when cleaning up the mats formed by cyanobacteria. The idea is to remove the organic carbon that the cyanobacteria create through photosynthesis and then store in the mats to be used for growth and reproduction.

All of this above IMO

Sincerely Lasse