# Cyanobacteria and Nitrate dosing - a myth?



## CrypticLifeStyle (Jan 16, 2013)

I dont understand where you'd want phosphate levels high either as it's a dissolved organic matter which help feed into the criteria of what cyano needs, same goes for nitrates. But also remember low flow areas in a saltwater tank as well as a freshwater tank are also big contributors to the criteria needed. But you can keep micro algae in a tank with zero nitrates, it just starts to filter feed.

Anyways dosing nitrates to me sounds counter productive to getting rid of cyano. I think he's basing that off of the redfield ratio.


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## plantbrain (Dec 15, 2003)

PO4 can be all over the place, NO3 is the main factor.
Keep it 10 ppm or a tad higher most of the time.

Once BGA starts, it's tougher to beat back, even if you return to the higher dosing, but it's generally not as aggressive.

Rotting roots and poor growth, melting leaves etc, these are good signs that BGA can grow. Low/absent NO3 as well.
If planted freshwater tanks:
Excess PO4 does NOT cause any algae bloom of any sort. I've made this as clear as possible going on 20 years. It's a myth and baloney. A good myth is hard to kill. Algae is rather easy to kill by comparison.
I marine planted tanks, PO4 at about 0.4 ppm causes a diatom bloom typically, I've found few who have NOT report this observation. 
So not BGA, but diatom filamentous species.
BGA is likely from die back and then less PO4 uptake by corals or the skimmer or refugium etc, generally something organic loading in nature for marine systems.
KNO3 dosing may help prevent the return in some of those systems, but not others.

But let's keep it it limited to Freshwater planted.


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## CrypticLifeStyle (Jan 16, 2013)

Can you explain to me how high p04 is not a contributor in the growth of algae?

I'm honestly very interested cause in 1998 i had a water volume algae bloom in my clown loache breeding tank while i was on vacation. 

I spoke with Mr. Ellis London over at Tropical Isle in my state who has a degree in Ichthyology, and marine biology from Boston University, and a chemistry degree from Harvard University tested my water, everything was in the norm, except for my phosphate levels that had built up from plants that died, or were dying in the tank. 

He gave me a bottle of kent phosphate remover, gave me directions how to use it. A week later, and a couple water changes the algae bloom was gone. So if it's true phosphates play no role in algae, how did that scenario fix itself? I'm generally curious as this is all news to me, especially after so many people i know have gone through the same scenario, with the same end results.


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## Canuck (Apr 30, 2009)

Best analogy I can think of is saying PO4 causes algae is like saying pizza causes teenagers. You can have very high levels of pizza and no teenagers or conversely you can have very low levels of pizza and high levels of teenagers. A large number of people dose hugely excessive amounts of po4 with no problems. This would be impossible if phosphates "caused" algae. Is PO4 a nutrient that algae needs? For sure. Its also a nutrient that plants need. My experience is that plants will suffer from deficiencies long before algae will. Once the plants start suffering and "leaking" organics and nutrients, you can forget about limiting nutrient availability for algae. Don't take me wrong, if you believe nutrient limitation worked for you, feel free to shout it from the roof tops. I've been at this since the 90's, I never had any success trying to limit nutrients to control algae. The only real long term success I had in reducing phosphates in the tank was by adding nitrates. After I started adding nitrate the plants started growing, then I had to add phosphate...


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## plantbrain (Dec 15, 2003)

Them meddling teenagers


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## plantbrain (Dec 15, 2003)

CrypticLifeStyle said:


> Can you explain to me how high p04 is not a contributor in the growth of algae?
> 
> I'm honestly very interested cause in 1998 i had a water volume algae bloom in my clown loache breeding tank while i was on vacation.
> 
> ...



Yawn. A pee contest. A VERY weak comment for support. 
I could go there, but I sure do not need to. I didn't back in the 1990's, I do not now.


Here's my tank which I've detailed in the tank journals section: I dose 5ppm 2x a week as KH2PO4. Clearly not PO4 limited.

Does not say WHY algae does not grow in this tank or many others just like it, only say that it cannot be DIRECTLY due independent of other factors(a key point) to non limiting PO4 concentrations. 



I have a hundred more going back to 1990.

Let me see you prove that my tanks do not work and have algae issues.
The above and decades worth of examples clearly falsify the claim about PO4 and algae linked in planted tanks and in systems such as Florida lakes where there are large % of surface coverage of aquatic plants year round.
You add more PO4 to those lakes, you get more aquatic weeds. Same thing in the Evergaldes which is why that's an issue with PO4 loading. 

Most of the plants we grow are weedy fast growing plants.


The issue is rather straight forward why some folks see improvement, while others see slowed plant growth only when they limit PO4.
Liebig's law clearly predicts and explains this. 

If you become more limited with say PO4 than a low level of CO2, then the tank will improve(CO2 limitation is more detrimental than PO4 limitation), but if the CO2 is good in high PO4, then you will NOT see improvement by limiting PO4. Limiting PO4 more strongly than CO2 will shift the MOST limiting factor from CO2, to PO4. In otbherwords, you have DEPENDENCE on CO2 if your case, but it is independent in my case and many others.
In research, you'd have poor methods and dependency. You need a reference, you do not have one, or in otherwords, no "control" for the test. 

But on a more aquarist common sense approach: how can I have nice tanks with virtually any plant species and gardening methods, and no algae?
No matter what, this claim cannot possibly be correct.
There are many other possible options, but not this one.
The principle of falsification. It does not say what causes something, only what it _cannot be_.

Video if still unconvinced.
There's a few dozen folks on this web site who have been to my home and seen the tanks.







He's welcomed to try and outdo my tanks and explain how I add 10 ppm a week(I can add more, but it no longer helps growth, but does not cause algae) and I lack algae. He cannot. 
Algae are not limited in either case. They grow great at low PO4 and at high PO4.
The real issue is all about the plants limitation and Liebig's law. 

I've supported why both cases work. Regardless of degrees, the logic, not the person's degrees, should be able to explain why both cases behave the way they do. And I've also made mention of the methods issues involved.
I know this topic inside and out and have had discussions about this going back to the mid 1990's on the APD. That was long before forums and boards. 
Folks still think this and bad information is still repeated.
Next time, do NOT use degrees for support. It's always a red flag.


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## CrypticLifeStyle (Jan 16, 2013)

This was a 55g it's been 15 years since i had the issue, but if i remember right the nitrate readings were 25/30ppm when i got back from vacation which was 2 weeks in length. The plants were dead, so essentially there was no plants absorbing any of the phosphates as they were dead, and decaying. 

So dosing for a planted tank, opposed to a tank with dead, and decaying plants to me present different environmental scenarios. 

Now when Tom states "Excess PO4 does NOT cause any algae bloom of any sort. I've made this as clear as possible going on 20 years. It's a myth and baloney." 
But i think we can all agree it can play a role in being a contributor in algae growth, as several factors are needed together being contributors, right? 

In my scenario with that tank, while nitrates were high, they wern't too high, phosphates were very high but unfortunately i dont recall the reading Mr. London mentioned, and from my knowledge phosphate sponges only remove phosphates, not nitrates. 
So 2x water changes of 50% in a week bringing the nitrates below 20ppm, and not using a phosphate sponge would of alleviated water volume algae? 
Or whats being stated is Phosphates are not the lone culprit?



plantbrain said:


> Yawn. A pee contest. A VERY weak comment for support.
> I could go there, but I sure do not need to. I didn't back in the 1990's, I do not now.


Excuse me? Thats the response for asking a general question while sharing the scenario i went through in hopes of an explanation?


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## randerson (Sep 5, 2013)

It seems like there is a lot of anecdotal evidence going around. I've read through some studies on cyanobacteria nutrient limitation on reefs and basically many of them contradict each other. It seems that some species of cyanobacteria utilize phosphate and others don't. So the next question is what species do we tend to get in aquariums?

Read the discussion section in this paper.


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## CrypticLifeStyle (Jan 16, 2013)

For the record since somehow questioning a snark response to my original post by asking for information, while relaying a scenario, and information from my end that was giving to me 15 years ago, who gave it to me, and how it panned out is some how turned into me pushing a myth, or saying he's wrong is simply not the case. I was generally interested, and hoping for a explanation.


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## DarkCobra (Jun 22, 2004)

If you starve BGA of phosphate, it will die. Nothing strange about that.

But does excess phosphate (PO4) cause algae? That depends. First of all, "excess" is a very vague term. I consider it to mean "anything more than the plants can use, so deficiency can't occur" (non-limiting), rather than "too much". When does it go from "excess" to "too much"? 1-2ppm is excess in most tanks, yet considered normal and acceptable. 30ppm, the highest PO4 I've run a tank, is also excess, but not necessarily too much. Replacing the water entirely with dry KH2PO4 is also excess, and finally too much, because I guarantee you'll then have some kind of problem. 

I can take a stable, well-set up tank with good parameters across the board, and dump in huge amounts of PO4 just like Plantbrain. No algae results.

I can take another tank with some pre-existing parameter issues and a bit of algae, and dump in the same amount of PO4... BOOM, algae explosion. Or I can cut PO4 dosing, and make some of the algae that was originally there go away.

It's easy to say that PO4 is to blame, but it really isn't. Everything works in concert, and problems may not only add - but _multiply_. Even if the individual problems were too small to cause any visible issue on their own, combined they can result in disaster.

Moderate excess is rarely a problem by itself. A huge excess can be. And you cannot assign a fixed ppm to what constitutes "too much". It differs according to all the other parameters.

As for BGA, I have personally had it defy every theory I've seen. It has appeared, thrived, and refused to be cured; regardless of nitrate, phosphate, oxygen, etc.

But I don't get it anymore. Ok, there's some scattered on filter outflows, but it never invades my tanks. What changed? There is nothing I can point at and say, "change _this_ to prevent or cure it". The only thing that has really changed is that my overall skills have improved. I keep parameters closer to optimal, stable, plants well-trimmed and maintained, and so on; without really having to think about it much anymore. When I get lazy or inconsistent, make errors or misunderstand what plants need to be healthy in any particular circumstance, that's when algae shows up.

Sorry it's not an easy, well-defined and therefore reassuring answer. I wish it was. But when it comes to eliminating BGA through nutrient control, you'll just have to experiment and see what works (if anything) _in your own tank_. Or use blackouts, spot treatments, antibiotics, etc. I always preferred Erythromycin myself. But it can fail if there are spots deep in the substrate it cannot reach, especially with soil and sand. And BGA will reoccur if you reintroduce it from an outside source - including your other tanks, if they have latent BGA. So no matter what you do, _always_ follow up by making sure your parameters are good, plants are healthy, substrate isn't dirty or anaerobic, etc.

Plantbrain has many years on me in this hobby. Keeping everything perfect is a complete no-brainer for him, and it has been for a long time now. Years ago we used to have arguments which make this thread look downright cordial. "How can you possibly claim excess PO4 doesn't cause algae, when I can induce algae with it again and again?" I'll tell you why. Every other parameter, except the one he's altering, is _perfect_. And therefore when he alters a single parameter, the typical result is that nothing bad happens. Whereas the result for others can be different. That is a lesson I will always try to remember when giving advice, and the grain of salt I apply to his.

No scientific references today. Just my experience and opinion, take it or leave it. :icon_wink


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## randerson (Sep 5, 2013)

Sound advice DarkCobra. It's clear that BGA uses a lot of things to grow and to point to one thing as the cause is out of line with that. 

I started this thread because obviously I have a BGA out break. It started after I neglected to refill my CO2 tank and hadn't done a water change in a while. Fixed those two things, doing a blackout, and some spot treatment and we'll see if it goes away. 

I do think there are things to be learned by identifying the exact species and then attacking it based on what nutrients that species uses.


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## CrypticLifeStyle (Jan 16, 2013)

Hey randerson, sorry for hi-jacking part of your thread


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