Randy Holmes-Farley
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Reefkeepers are extraordinarily fortunate that there are so many strong negative feedback loops in reef chemistry, and relatively few positive feedback loops.
A positive feedback loop is a situation where as a process proceeds, it alters things in a way that makes the process go faster and faster.
A negative feedback loop is a situation where as a process proceeds, it alters things in a way that makes the process slow down.
Imagine a couch on fire in a house. As the fire burns, oxygen becomes depleted. The reduced oxygen can slow down the burning process. That is a negative feedback loop.
Imagine instead if the products of the fire were able to actually feed the fire and make it burn faster. In such a positive feedback loop, the couch might burn faster and faster and maybe explode. That is actually how some nuclear weapons work, with the production of high energy neutrons triggering the fission of more fuel, releasing more neutrons, which trigger more fission...
In general, negative feedback loops enhance stability, and positive feedback loops cause instability.
All of the following examples display the properties of a negative feedback loop, except one. That one is a positive feedback loop. Think about them in a typical reef aquarium setting, not a contrived situation.
Which of the following feedback loops is sometimes a positive feedback loop, where all of the others are more often negative feedback loops?
Each is listed as a measured value, and a process that depends on and also changes that value.
A. Silicate and diatom growth
B. Aquarium water temperature and evaporation
C. Alkalinity and SPS coral calcification
D. Calcium carbonate surface area and abiotic precipitation of calcium carbonate
E. pH and abiotic precipitation of calcium carbonate
Good luck!
.
A positive feedback loop is a situation where as a process proceeds, it alters things in a way that makes the process go faster and faster.
A negative feedback loop is a situation where as a process proceeds, it alters things in a way that makes the process slow down.
Imagine a couch on fire in a house. As the fire burns, oxygen becomes depleted. The reduced oxygen can slow down the burning process. That is a negative feedback loop.
Imagine instead if the products of the fire were able to actually feed the fire and make it burn faster. In such a positive feedback loop, the couch might burn faster and faster and maybe explode. That is actually how some nuclear weapons work, with the production of high energy neutrons triggering the fission of more fuel, releasing more neutrons, which trigger more fission...
In general, negative feedback loops enhance stability, and positive feedback loops cause instability.
All of the following examples display the properties of a negative feedback loop, except one. That one is a positive feedback loop. Think about them in a typical reef aquarium setting, not a contrived situation.
Which of the following feedback loops is sometimes a positive feedback loop, where all of the others are more often negative feedback loops?
Each is listed as a measured value, and a process that depends on and also changes that value.
A. Silicate and diatom growth
B. Aquarium water temperature and evaporation
C. Alkalinity and SPS coral calcification
D. Calcium carbonate surface area and abiotic precipitation of calcium carbonate
E. pH and abiotic precipitation of calcium carbonate
Good luck!
.