Great. I may be sloshing the vibes I am getting from the op onto you. If that is the case I apologize! I put him on ignore because he is damaging my calm.
You previously wrote -
I am trying to figure out what those conditions are, and what lighting you are mentioning. I don't know of any photosynthetic coral that will grow in conditions in which problematic algae also won't grow, so I was looking for clarification on that specific point.
I get the idea of comparative advantages, and it is a good discussion, but not a practical one IMO. Any enviornment that you grow photosynthetic coral in will also grow algae. I get the idea, but it doesn't actually pan out that way in practice because algae is much better at life then coral and can grow with less light and less nutrients that the corals we are keeping need.
I have yet to see someone deal with algae only by using an ATS, but every time that seems to get chased down there are other algae mitigating factors at play in the system.
There are a lot of ideas that seem to make sense in this hobby, but with further practical experience don't pan out.
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!
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.
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. 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. 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.
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.
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).
With that said, I'll try following my second motto at the top, I appreciate your experience and am always interested in hearing other people's strategies for reefing!
