In research, you MUST HAVE aquatic plants present to suggest nutrients and algae blooms within planted aquariums. Not doing so.... skews the research and does not support your contention. Many studies suggest N and P induce algae blooms, but such systems lack submersed aquatic plants at 30-100% coverage. You need around 30% or more to have the plants define the system from the top down, not bottom up control like with nutrients.
Bottom line is cyanobacteria are phosphorous dependent. Period. No one is yet to dispute that.
Well of course. That is why it is called an essential element. Why is this even stated?
I stated that higher concentrations of PO4(eg non limiting to both plants and any algae/BGA) do NOT induce BGA in aquariums, if they did, everyone that doses EI would have a lot of BGA, but that is not the observation or the case.
This is independent of any other factors.
So higher levels of PO4 do not induce BGA/algae. You cannot get around this specific planted tank observation. Where there are a high % surface coverage of plants, there is no correlation between nutrients and algae.
I suggest a good read: Bachmann 2002.
What is a limiting range for BGA?
What is the specific species that infest our tanks?
This is about the only genus we have issues with.
So the rest of those species are not particularly specific to aquarium.
The South Florida water management district has a periphyton group, they study BGA crust in the Everglades. Shallow well planted regions. To restore the Everglades back to it's functional state, they need roughly under 10 ppb BILLION, ideally around 3-10ppb or so as I recall. Submersed plants around 50ppb, so you will limit and hurt plants long before you limit BGA via dosing.
It's like trying starve the mice while also feeding elephants at the same time at the same troft.
This is not a hypothesis, nor a theory. This is clearly stated in the literature, in more than one source. Quote your source stating cyanobacteria aren't phosphorous dependent or drop it. Seriously.
Here's the disconnect: Equate non limiting values with a required essential element. No one is debating whether P is an essential element. Where did this come from? I never once brought that up.
I simply have siad that at higher concentrations, in the 1-10 ppm range for PO4, 2-3 orders of magnitude higher than the limiting range, that BGA is a non issue due independently from dosing KH2PO4 and KNO3.
You are suggesting that there is dependency.
Above 10-20 ppb, they are independent, it's only when you get well below the limiting values for plants, can you start to limit BGA with P. Few test kits even have decent accuracy and measurement this low, it can be done, but error values of 3ppb and a range of 10ppb or under are extremely tough for the periphyton group, I think aquarist will have a tough time.
The presence of excess phosphorous doesn't guarantee that a cyanobacteria bloom will occur, I never stated that.
You suggested it does. Now you want this both ways?
But cyanobacteria blooms do occur when there is excess phosphorous.
Disprove that. That it hasn't happened in your tank does not prove that excess phosphates and excess nitrates are not the cause of cyanobacteria blooms.
Actually it does. Here's the rub: INDEPENDENT
of other factors. You do not get to say it is independent and dependent, it is on eor the other, it cannot be both for the same system.
If you have dependency on other factors, of which there may be many, then why even worry about N or P being at a higher level? Non limiting is non limiting regardless.
That's why they use non limiting nutrients to study other factors like light and CO2 for plant growth. It's no longer dependent when you dose that way.
Or if they want to study say just P, they provide all other factors at non limiting nutrient values, thus only P is the dependent variable. The experiment typically has an upper bound(eg non limiting) and a lower bound(DI water etc, no ferts) and then a range of concentrations in between.
Adding more will not induce BGA. If there was dependency independent of the other factors, we would HAVE to have a high % of aquarist who dose KH2PO4 and KNO3 at say 5ppm PO4 and 15-20ppm a week have BGA, that is simply not the case. This clearly demonstrates that adding "excess" PO4 or NO3 does not induce algae or BGA. It's repeatable and has been for about 15 years now in the hobby.
This is not a new thing.
Anytime two species utilize the same resource, they compete (also see above link.)
Not if they occupy a very different niche both spatially, temporally and in size. I guess mice and elephants cannot coexist since they are both herbivores eh? Light is about the only thing algae and plants really compete for and this is even much more reduced for the genus that pesters us.
Until you get insanely low values, you are not going to have any competitions and if you do, it'll be the plants that die/stop growing long before the BGA.
The problem stated by the OP was continual cyanobacteria blooms. I didn't offer speculation that it could be low O2 or some other cause. I offered actual conditions that are conducive to cyanobacteria blooms and suggested remediation. What was your reply? Something along the lines of we can't be sure what causes that.
I can only be sure of what I can falsify, we can never be 100% certain of cause and aquariums in the little glass box is a very different issue than a lake, or a stream, or the middle of a gyre in the Pacific. We deal with one genus(maybe a couple more, but they are rare) of BGA and controlling it is fairly straight forward.
Mostly through growing plants, not trying to outwit algae.
Paul Sears and Kevin Conlin long ago proposed this:
It's just a hypothesis, so I dosed more and waited for algae, instead, I had awesome plant growth and no algae.
Conclusion, the hypothesis must be false(this next part is important)... independent of other factors. It does not say that removing all essential elements is not dependency
Paul even made the statement we need some PO4...and that 0.00ppm is bad and will limit plant growth as well. What I showed was that it need not be in this tight narrow range say +/- 0.1 ppm and a target of 0.2ppm.
I have had high PO4 for the last 15 years and I have many many examples of some nice planted scapes and plant growth, so have many others.
Research is a good place to start, but it does not imply that the same principles work in aquariums. There needs some corroboration in what we see in the field and aquarium. Bachmann's study does that. In a lake without much plant growth % cover, I agree adding ferts will likely increase algae total concentrations and diversity. The key is % plant coverage. Same in our tanks and even in the pond hobby. If you have say 30-50% or more coverage, you likely will have a plant defined system.
Why this is I can only speculate. I do not know much, but I do know that adding a specific non limiting range of nutrients does not induce any algae.
Final note, do not take things personally. This is a discussion about plants, stick to that.