Cyano question ....

[taricha]

So if dosing nitrates can work sometimes and sometimes not......what is my next step if the nitrate dosing doesn’t work??

Poor OP. Just wants to get rid of cyano. And we're working to figure out how to grow the stuff.
If you want to try some of the theory we're discussing, then in addition to nitrate it may be interesting to vacuum the cyano/debris and top layer of sand at the trouble spots and sprinkle fresh aragonite sand in its place.
Adding nitrate, removing particulates, destroying nutrient gradient in the sand, adding fresh aragonite phosphate sponge.
That should cover most of our favorite theories at the moment. [emoji846]

 

[grantUcorals]

Poor OP. Just wants to get rid of cyano. And we're working to figure out how to grow the stuff.
If you want to try some of the theory we're discussing, then in addition to nitrate it may be interesting to vacuum the cyano/debris and top layer of sand at the trouble spots and sprinkle fresh aragonite sand in its place.
Adding nitrate, removing particulates, destroying nutrient gradient in the sand, adding fresh aragonite phosphate sponge.
That should cover most of our favorite theories at the moment. [emoji846]

[emoji23][emoji23][emoji23][emoji23] yeah you guys are amazing and way over my head on this!! Lol

Y’all can keep on going though! I am currently still doing my 40 gallon water changes every 9 days and siphoning out as much cyano as possible on sand....it’s not really on the rocks that much so no worries there, I just blow the off with a turkey baster ....

Dosing nitrates slowly also and finally got them to read something and they are at about 1-2 right now

I’ll keep you guys updated!

 

[Lasse]

I think both of us are right. There is some type of chemisorption, but it seems to be more effective in lower pH (below 7) or very high pH but there is also forming of calcium phosphate - this is more depending on pH above 7.6 (if I remember right) and the concentration of Ca ions. PH below around 7.6 will release the PO4 from calcium phosphate

Some authors also state

Stumm and Leckie (1970) suggested that the initial uptake of phosphate on calcite occurs by chemisorption, followed by a slow transformation of amorphous calcium phosphate to crystalline apatite

This article is rather good.

I found another article here. I have not read through the whole article yet - but I think it will give valuable information about the process

According to add HCO3 ions - it will stable the pH around 8.1 (when equilibrium with CO2 in the water and air) adding more and more HCO3 will slowly rise the pH. I have done this by own experiments. I have measured pH in freshwater denitrification filter and with higher alkalinity - pH rise to around 8 - 8.3.

Sincerely Lasse

 

[Dan_P]

I think both of us are right. There is some type of chemisorption, but it seems to be more effective in lower pH (below 7) or very high pH but there is also forming of calcium phosphate - this is more depending on pH above 7.6 (if I remember right) and the concentration of Ca ions. PH below around 7.6 will release the PO4 from calcium phosphate

Some authors also state This article is rather good.

I found another article here. I have not read through the whole article yet - but I think it will give valuable information about the process

According to add HCO3 ions - it will stable the pH around 8.1 (when equilibrium with CO2 in the water and air) adding more and more HCO3 will slowly rise the pH. I have done this by own experiments. I have measured pH in freshwater denitrification filter and with higher alkalinity - pH rise to around 8 - 8.3.

Sincerely Lasse

Very good reading material. Thank you @Lasse

 

[Dan_P]

If it is a strong denitrification below the mats - the HCO3 ion added will secure a pH around 8.1 - 8.2 in the pour water (IMO)

Sincerely Lasse

@Lasse, there cannot be “strong” denitrification under cyanobacteria mats which results in a rise in pH because there isn’t that much nitrate available. For every 10 ppm of nitrate reduced, only 0.16 meq/L HCO3 is produced.

 

[Lasse]

@Lasse, there cannot be “strong” denitrification under cyanobacteria mats which results in a rise in pH because there isn’t that much nitrate available. For every 10 ppm of nitrate reduced, only 0.16 meq/L HCO3 is produced.

0.16 mEq/L is is equal to 0.16 mmol/L - which correspond to 0.61 mg/L HCO3 -> 0.16 * 2.8 = 0.45 in dKH. I think that this will stabilize the pH around 8. And that is enough to keep most calcium phosphate stay as just calcium phosphate. Normally I want over 2 ppm NO3 - it will give 0.09 dKH if the permeability through the mat is the same for NO3 and HCO3 However - when you refer to lower pH will release more PO4 - I suspect that you talk about calcium phosphate. It dissolves at pH about 7.7 and lower.

I did a funny experiment once. In a freshwater tank I had rather high PO4 levels (more than 1 ppm) There was a high content of calcium in the water > 50 ppm. It was waste water. Heavy light and the pH rise to over 9 during daytime and got down to below 7.5 during nighttime. We measured the PO4 - nearly 0 just before the light gets out and up to nearly the same level as the day before when pH get low

Studies from freshwater lakes in Sweden and Denmark has shown that 2 ppm NO3 in the bottom water is probably block hydrogen sulphide production. These lakes (with > 2 ppm NO3) did not show up any pelagic cyanobacteria bloom - lakes with lower or zero ppm NO3 in the bottom water had dense blooms during summer. The study was done with a pelagic type of cyanobacteria that shows that it had a vertical migration over 24 hours. Daytime up in the sun and propagate - during night down in the anaerobic bottom water picking up PO4 probably released by hydrogen sulphide This study was an eyeopener for me according to cyanobacteria. Unfortunately, this report is only in Swedish - and it is huge.

Here is a English summary of the report - I can post the whole report - but as I said - it is in Swedish

Summary This study has focused on why, and when, cyanobacteria (blue-green algae) mass develop in fresh water. Eight different lakes were studied regarding phytoplankton composition and physical and chemical factors. The phytoplankton were divided into several groups based on their ability to perfom vertical migrations and their potential to develop heterocytes (nitrogen-fixing cells). The results were analysed with stepwise regression and principal component analysis (PCA). Total nitrogen, measured at the bottom was the chemical variable that strongest correlated (positively) with the biomass of non-migrating algae. The chemical variables that correlated strongest to vertical migrating cyanobacteria without heterocytes was total phosphorus at the bottom (positive correlation) and nitrate at the surface (negative correlation). A similar, but weaker, relationship was observed between heterocystous cyanobacteria, nitrate and total phosphorus. Nitrogen at the bottom was the most important chemical variable that separated the migrating algae from the non-migrating algae. A positive relationship occurred between nonmigrating algae and nitrogen at the bottom whereas the relationship was inverse regarding the migrating phytoplankton. Our interpretation of the results regarding why vertical migrating phytoplankton proliferate at low nitrogen levels is partly that nitrogen deficit is compensated by cyanobacterial nitrogen fixation and partly that nitrogen deficit at the bottom permits release of phosphate from the sediment. Low levels of nitrate in the sediment may cause deficit of electron acceptors at bacterial decomposition of organic material. Instead of nitrate, sulphate can be used as an electron acceptor which results in the formation of hydrogen sulfide. The presence of hydrogen sulfide, in turn, causes the release of phosphate from the sediment. Results from the retrospective study in Lake Finjasjön, Sweden, showed a strong correlation between internal phosphorus release and the biomass of vertical migrating algae and total algal biomass respectively. A negative relationship was found between internal phosphorus release and non-vertical migrating algae. There existed no relationship between the biomass of any algal group and the net release of nitrogen whatsover. An increase in nitrogen in the lake did, consequently, not effect the algal biomass in the same way as phosphorus. These results confirm earlier discoveries by Schindler and Hellström which showed that the algal biomass was governed by the phosphorus concentration whereas the nitrogen deficit is compensated by nitrogen fixation.

Sincerely Lasse

 

[Dan_P]

0.16 mEq/L is is equal to 0.16 mmol/L - which correspond to 0.61 mg/L HCO3 -> 0.16 * 2.8 = 0.45 in dKH. I think that this will stabilize the pH around 8. And that is enough to keep most calcium phosphate stay as just calcium phosphate. Normally I want over 2 ppm NO3 - it will give 0.09 dKH if the permeability through the mat is the same for NO3 and HCO3 However - when you refer to lower pH will release more PO4 - I suspect that you talk about calcium phosphate. It dissolves at pH about 7.7 and lower.

I did a funny experiment once. In a freshwater tank I had rather high PO4 levels (more than 1 ppm) There was a high content of calcium in the water > 50 ppm. It was waste water. Heavy light and the pH rise to over 9 during daytime and got down to below 7.5 during nighttime. We measured the PO4 - nearly 0 just before the light gets out and up to nearly the same level as the day before when pH get low

Studies from freshwater lakes in Sweden and Denmark has shown that 2 ppm NO3 in the bottom water is probably block hydrogen sulphide production. These lakes (with > 2 ppm NO3) did not show up any pelagic cyanobacteria bloom - lakes with lower or zero ppm NO3 in the bottom water had dense blooms during summer. The study was done with a pelagic type of cyanobacteria that shows that it had a vertical migration over 24 hours. Daytime up in the sun and propagate - during night down in the anaerobic bottom water picking up PO4 probably released by hydrogen sulphide This study was an eyeopener for me according to cyanobacteria. Unfortunately, this report is only in Swedish - and it is huge.

Here is a English summary of the report - I can post the whole report - but as I said - it is in Swedish



Sincerely Lasse

Thanks much @Lasse! I understand the concepts more clearly now. I need to pay closer attention to pH in my next cyanobacteria study.

In the last study, I added a small amount of aragonite sand from an aquarium to the cyanobacteria medium. The sand was thoroughly rinsed before using. The odd thing was that Spirulina (my current study species) barely grew in the container with sand but did well in an identical container without sand. I am currently trying to determine why.

 

[grantUcorals]

Hey guys!! It’s been a minute but I’m STILL fighting the cyano!!! My acros and other corals are still looking good and I still believe it’s because my nitrates are TOO LOW but I wanted some other opinions on my ATI lab results and maybe I’m missing something else?? Thanks in advance!!

 

[ScottB]

I've made this claim myself, but we may need to re-evaluate it...


...heterocysts would be a giveaway that we're seeing nitrogen fixing, but I've never seen heterocysts in the cyano in aquarium benthic mats. I've seen mostly oscillatoria with some spirulina well represented and other things I can't put a name to that show up rarely. Lyngbya also but usually it gets called a hair algae and not a mat. anyway. None of the nitrogen fixers listed in your great link are things that we observe plaguing our tanks. Does that mean our cyano don't fix nitrogen? well, I ran across two papers recently that mentioned nitrogen fixing in oscillatoria: one said they do and one said they don't. :-/
Dan has observed nitrogen stress response in his lower N cultures of spirulina, a color change where they eat their phycobilin pigments which they keep as a spare source of N.
I've observed oscillatoria grow strongly in corners of my sump where I sprinkled NaNO3 pellets as a test. then recede when I stopped, then start back up when I added more pellets. When I did the same in the sandbed - I got nothing. hmm....
What to make of all this?
Not sure, but I lean toward the interpretation that our cyano are not nitrogen fixers, but they are well adapted to nitrogen stress - Dan's experiment the cyano kept growing as it ate its pigments. That's a nice trick! And many tanks with undetectable Nitrate have plenty of happy cyano.


What I can say definitively is that beakers kill cyano. If one constructed a reef tank entirely out of lab beakers, cyano would struggle mightily to ever grow in that system.


I see the same, but my interpretation is slightly different. cyano colonizes recently dead coral, recently dead rock that got cleaned/ had organisms exposed, and recently dead algae. It seems great at exploiting conditions in/around decay. [Black band disease is - in part - an oscillatoria that can eat a cm of live coral per day!]
What if the most important part of the way cyano gets N that others struggle with is not the nitogen fixation, but is instead the remineralization and nitrification see steps #6 & 7 from subsea's link. This is why we keep looking at the cyano associates.

(sorry that got long...)

You had me at: "What I can say definitively is that beakers kill cyano. "

That was priceless. I was all hyped up that @taricha was on to something by isolating cyano. Great line that even a non-scientist would get.

Playing catch up but watching this thread. While cyano is not a current problem of mine, I've lost count of how many tanks in our town have it to varying degrees. Perhaps I will recommend dropping beakers in each one.

 

[bar|none]

My first response to cyano mats is to rise NO3 or PO4 levels if they are very low or zero. I start to disturb the mats to every evening, because they usually have their optimal distribution just before the lights go out. snip...

This worked for me, and thank you!

 

[Dan_P]

Hey guys!! It’s been a minute but I’m STILL fighting the cyano!!! My acros and other corals are still looking good and I still believe it’s because my nitrates are TOO LOW but I wanted some other opinions on my ATI lab results and maybe I’m missing something else?? Thanks in advance!!

Sorry, no insights based on your test results. Will you be trying nitrate dosing?

 

[grantUcorals]

Sorry, no insights based on your test results. Will you be trying nitrate dosing?

I have been trying a lot...
I'm dosing the bright well nitrate product about 12ml a day
Skimmer runs at night only with no collection cup on it for about 10 days
and over the last month or so Ive added more fish and feed like 2-3 times a day

the next step for me is setting up nitrates on a doser and just give it time and see what happens!

 

[Bryknicks]

I have been trying a lot...
I'm dosing the bright well nitrate product about 12ml a day
Skimmer runs at night only with no collection cup on it for about 10 days
and over the last month or so Ive added more fish and feed like 2-3 times a day

the next step for me is setting up nitrates on a doser and just give it time and see what happens!

Just wanted to add that I have done the nitrate dosing and that worked for me. My PO4 levels were between .02-.08 and my nitrates undetectable before hand when I had mats contstantly growing on the sand bed. After roughly 2-3 weeks of nitrate dosing I have stopped and stayed a constant 10 NO3 and .00 - .04 PO4 and the cyano has not come back.

 

[grantUcorals]

thanks for the reply!!! I think my situation is just like yours!!!

What nitrate product did you use?? And how much water is in your system? And how much did you dose a day on your system? Just curious!!!

 

[Bryknicks]

thanks for the reply!!! I think my situation is just like yours!!!

What nitrate product did you use?? And how much water is in your system? And how much did you dose a day on your system? Just curious!!!

I have an 80 gallon system. I used spectricide stump remover (Potassium Nitrate) that I found on a bunch of threads here. I made a solution modeled after a member on here. It's 40 grams of potassium nitrate to 1 gallon of RODI water. 1ml of this solution will raise the nitrate 0.8ppm per 2 gallons of system water. I was dosing roughly 60 ml of this daily for 2 1/2 weeks until my tank was measuring nearly 10 NO3 prior to dosing. Then I slowly dwindled down the dosing until I stopped and thus far the cyano has not returned and my nitrate levels have been holding steady.

 

[grantUcorals]

I have an 80 gallon system. I used spectricide stump remover (Potassium Nitrate) that I found on a bunch of threads here. I made a solution modeled after a member on here. It's 40 grams of potassium nitrate to 1 gallon of RODI water. 1ml of this solution will raise the nitrate 0.8ppm per 2 gallons of system water. I was dosing roughly 60 ml of this daily for 2 1/2 weeks until my tank was measuring nearly 10 NO3 prior to dosing. Then I slowly dwindled down the dosing until I stopped and thus far the cyano has not returned and my nitrate levels have been holding steady.

That is awesome!!! I know a lot have used that stump remover but I’m just nervous to use it because it’s stump remover lol....no idea why!! So now that cyano is gone, so you still dose some nitrate? Or are you not dosing anything now?

 

[Bryknicks]

That is awesome!!! I know a lot have used that stump remover but I’m just nervous to use it because it’s stump remover lol....no idea why!! So now that cyano is gone, so you still dose some nitrate? Or are you not dosing anything now?

To my understanding it is almost pure which is why it is used. You can buy lab grade "pure" off the internet but this is the same for a cheap price and at the local box store.

I'm currently not dosing any nitrates. After reading a lot on here I believe I did not have a proper nutrient balance between NO3 and PO4. If anything I upped my feedings, but I personally would say not enough to make a difference. I'm keeping an eye and testing every few days just to make sure, but keeping my fingers crossed for now!

 

[grantUcorals]

To my understanding it is almost pure which is why it is used. You can buy lab grade "pure" off the internet but this is the same for a cheap price and at the local box store.

I'm currently not dosing any nitrates. After reading a lot on here I believe I did not have a proper nutrient balance between NO3 and PO4. If anything I upped my feedings, but I personally would say not enough to make a difference. I'm keeping an eye and testing every few days just to make sure, but keeping my fingers crossed for now!

Awesome!!!! Thanks for you input and experience!!!! I’ll be getting some more nitrates ASAP!!! I definitely think Mine is an imbalance of nutrients also! Thanks again