I'll start by saying that I always try my best to stick to the facts of the discussion and not to make any comments or opinions on people in the discussions. I also live by the mottos of never back people into corners and always give them a path out. Impartiality is the way to go!
Now, back to the science:
As the comic suggests, life is often more complicated than we give it credit, and simple solutions of the sort “set your [insert fav param here] to X ppm and all will be solved!” are rarely correct. So if you're looking for specific parameters that will cure your tank of algae, you won't find them here. Tank to tank, there are a lot of variables at play and things are very dynamic. But this is the basis of my point/
And the basis of my points in this thred regarding the topic - all you need to do to get rid of algae problems is add an ATS. This is what the current thread is about. That seems like a simple but wrong answer given the number of tanks we see that run ATS and still have algae problems.
Saying something is/isn't practical is subjective; if someone uses it, it can be practical to them, and vice versa if they don't. It's not the main point of my discussion, but I also hope to convince you that thinking of things as dynamic processes with relative advantages is an intuitive framework for looking at how your tank operates and can lead to real actionable decisions.
Check out the skeptical reefkeeping series because I agree with all that you have to say about science. I aslo think that mind stories live in the theoretical, and we convince ourselves that actions have efficacy when they don't, or we don't know they really do, because they make sense in our minds. However, efficacy in practice is another matter, and the list of ideas that make some sense theoretically but don't pan out practically in this hobby is long - ginger curing ich, the ecoaqualizer did what it was claimed to do, your fish get diseases from frozen food, etc. So, at some point, we need to leave the theoritical and look at the actual. This was the basis of my questions to you.
First off, your initial question was why algae is able to grow in one place but not another. The answer is in relative advantages. Ever notice how certain algae/corals grow better in certain parts of your tank? It's because of the relative advantages of that spot. Maybe more lighting, maybe better flow, maybe nutrients/particulares seem to fall on that spot. Now if one spot has an advantage, things can grow faster there than at other spots and suck up all the nutrients available.
Or herbivores are keeping it in check better in some areas than others, which we can expect given not all herbivores can get to every spot. Also, if you let the algae in a tank grow without a check, it can grow in just about every spot in that tank, we see examples of this daily.
I want to posit that our fish tanks are not so big that resources are infinite. We do in fact see measurable nutrients rise and fall (there is NOT an infinite pool of resources to replace any nutrient that gets taken in) so these fluctuations will have an impact on everything else in the tank depending on them. So, favoring a patch of algae in one place will have an effect on the growth of algae elsewhere in the tank.
Yes that is all theoretical (except that nutrients fluctuate (they do in the wild as well), and what I think we need to get away from to determine if a particular methodology generates the results it claims to produce. In practice, I am not aware on someone running a tank with no herbivores beating an algae issue by growing algae in anothe part of the system. In practice, in the majority of our tanks, the amout of any nutrient that algae needs to live is much less than the amout our corals need to live.
Also, as others have mentioned, nutrients are not just N and P but other micro/macro nutrients that we aren't even aware of, so it's nice that we can just make algae compete with itself! Notice, however, that I am not saying what the magnitude of this effect will be, as there are a lot of other factors at play that change with one's reefing practices. I'll leave sizing of refugiums/ATS (or even desire to use one at all) to people's experience, but not considering the comparative advantages of lights was a glaring omission in logic for a number of comments that I am trying to help out with.
And practically, we see a million examples of tanks with ATS having algae all over the place in the system, which makes me squint a lot at the idea that making algae compete with itself in our systems makes practical sense.
As for my issue with the statement that any condition that grows corals can grow algae: I don't like this statement because it's an absolute statement, which is almost always wrong (notice what I did there? Lol). A single counter example negates the statement, trivial ones being non photosynthetic corals living in total darkness or extreme deep water corals that can grow at depths that algae cannot. But as the initial comic I posted suggests, things rarely have simple answers and of course the details of what we're talking about matter.
However, we know the universe of discourse and we know we are not talking about extreme examples of animals that require no light. We are talking about reef tanks in general, and the majority of them have corals that require light. My statement that anywhere corals can grow algae can grow is in that universe of dicourse.
Among the spread of corals and algae, each has its own ecological niche, accompanied by unique nutrient requirements and acquisition. The benefit of thinking of things as dynamic processes with comparative advantages is that we can seek out what those conditions are for our tanks / husbandry practices. I can quote simple things like bluer lights or low iron but there is no general rule for every tank because we all have different goals. Maybe someone likes nems and the blue light is too detrimental to them. Maybe we like macro algaes in the tank so we regularly dose iron for them, or maybe we employ other algae removal techniques and up nutrients to bring out colors of corals. But the unifying framework here is that the creatures in these systems have varying nutrient requirements and using comparative advantages gives us knowledge to favor the things we like and disadvantage the things we don't. So, we can tilt the scales to favor our corals and disfavor algae (if that is our goal).
And the tilting of the scales is what led me to my questions to you. Staying in the theoritical, the scales tilt very little, so move to the practical. You had written "This is not true. There are a ton of conditions (whether through lights or nutrients) where corals can grow well but algae cannot." In general reef tanks, what blue light grows the corals we keep, and grows them well, but algae cannot? If I am understainding you, the answer is none right?
Fun discussion. Thanks!
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