Cont'd:
What's left? A tank with limited denitrification (because its slow and aerobic things happen fast) and a whole lot of other stuff in the water. Who comes to the rescue and thrives during these cycles? The next fastest growing groups...cyanobacteria, single celled algae, protists, ciliates, etc. Then they do their little cycle thing. And then the turf algae take advantage of the nutrients (the hair algae stage). Turfs get mowed down by all the little amphipods that are suddenly springing up cause they have a food source. Maybe you've bought some snails by now, too, or a fish. And the fish dies, of course, because it may not have ammonia to contend with, but is has water filled with things we can't and don't test for...plus, beginning aquarists usually skimp on lights and pumps initially, and haven't figured out that alkalinity test, so pH and O2 are probably swinging wildly at this point.
So, the algae successions kick in, and eventually you have a good algal biomass that handles nitrogen, produces oxygen through photosynthesis, takes up the metabolic CO2 of all the other heterotrophs you can’t see, the bacteria have long settled in and also deal with nutrients, and the aquarium keeper has probably stopped adding fish for a spell because they keep dying. Maybe they started to visit boards and read books and get the knack of the tank a bit. They have probably also added a bunch of fix-it-quick chemicals that didn’t help any, either. Also, they are probably scared to add corals that would actually help with the photosynthesis and nutrient uptake, or they have packed in corals that aren't tolerant of those conditions.
About a year into it, the sand bed is productive and has stratified, water quality is stable, and the aquarist has bought a few more powerheads, understands water quality a bit, corallines and algae, if not corals and other things are photosynthesizing well, and the tank is "mature." That's when fish stop dying when you buy them (at least the cyanide free ones) and corals start to live and grow and I stop getting posts about "I just bought a coral and its dying and my tank is two months old" and they start actually answering some questions here and there instead of just asking questions (though we should all always be asking questions, if not only to ourselves!).
So, ecologically, this is successional population dynamics. Its normal, and it happens when there is a hurricane or a fire, or whatever. In nature though, you have pioneer species that are eventually replaced by climax communities. We usually try and stock immediately with climax species. And find it doesn't always work.
Now, the "too mature" system is the old tank syndrome. Happens in nature, too. That whole forest fire reinvigorating the system is true. Equally true on coral reefs where the intermediate disturbance hypothesis is the running thought on why coral reefs maintain very high diversity...they are stable, but not too stable, and require storms, but not catastrophic ones....predation, but not a giant blanket of crown of thorns, mass bleaching, or loss of key herbivores.
This goes to show what good approximations these tanks are of mini-ecosystems. Things happen much faster in tanks, but what do you expect given the bioload per unit area. So, our climax community happens in a couple years rather than a couple of centuries. Thing is, I am fully convinced that intermediate tank disturbance would prevent old tank syndrome.
My advice on starting tanks is to plan the habitat you want. Find the animals and corals you like. Learn about the tiny area of the reef you will try and recreate, and do not try to make a whole coral reef in one tank. Then, purchase the equipment required to emulate that environment. Then, add the appropriate types of substrate (sand, rubble, rock, whatever) and wait long after “your tank water tests fine” before you add fish and corals. First, add herbivores and maintain water quality. Water changes, carbon, skimming, alkalinity, calcium. Keep the water of high quality, even for things you can’t test for. Wait a few months and enjoy the growth that will happen. Then, add some of the species that you plan to keep….invertebrates and corals. They help create the environment, and also photosynthesize, add biodiversity, stabilize nutrients, etc. Then….then….add fish. The fish will have a reef as their new home. They won’t be stressed by this variable bouilllabaise of water and a strange habitat that keeps changing as things are added or die. They will have a stable tank with real habitat, and then the original concept you imagined will have happened.
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Eric Borneman
