View Full Version : Why do elements have to be at certain concentrations?

02/12/2013, 01:56 PM
Why do elements have to be at certain concentrations in order for organisms to use them? Just a random thought I had. Hoping a chemist here can answer it for me in layman's terms.

We strive to maintain calcium around 420, magnesium around 1280, etc. If calcium drops to 300 for example, do the organisms just stop taking it out of the water or do they have to work harder to do so (since its in less concentration) or both?

What happens when concentrations exceed NSW by a lot (CA at 800 for example)?

Conversely, what is the benefit to having elevated levels of NO4 (I see a lot of hobbyists strive for 5ppm) instead of "just barely detectable" for their corals? Is it the hobbyists idea that since there is more in the column its easier for the organism to take it out and use it?


02/12/2013, 03:00 PM
Well part of it is just as you say. As the concentration of something like calcium goes down, it becomes harder to find that calcium ion that you need.

Another big part of it is reaction kinetics. The speed at which all of these chemical reactions that drive life is related to the relative concentrations of the reactants and products of that reaction. Less calcium means that the process of calcification goes slower.

Then there are the reactions that are reversible. In those reactions, if the concentration of the starting material goes so low that the reverse reaction happens faster than the forward reaction then you end up undoing things critical for life.

Concentration is one of the main driving forces in chemistry. All of these many things come together in a balancing act and it is those relative concentrations that set or upset that balance. I cannot begin to explain all of the places where it is important. But I hope this serves as a start.

02/12/2013, 03:16 PM
Ahh ok, that makes sense. Chemistry in school was not my strong suit, looking back i wish it was. Chemistry is one of my favorite aspects of the hobby and I am always trying to increase my knowledge in this department. Thanks for the reply!