How do Calcium, Magnesium, and Alkalinity Really Effect Things?

[Steensj2004]

Ok, so for a long time I've know what to keep my levels at. We all dose to keep our corals and water parameters healthy, but how do they really work? I keep my calcium at 425ppm, but what happens when it fluctuates slightly, what about the other elements? Are these elements in the water like gasoline for a car? For example, even when the gas tank is half full, the car runs just fine. Only when the tank is empty, does it have a negative effect, the car shuts down. So do these levels act as just an available source or does the concentration really make a difference?

[Amphiprion1]

The concentration actually does make a difference. In natural seawater, calcification is typically carbonate-limited. So a higher carbonate concentration can make a difference in growth, as many studies have shown. A greater concentration also increases the gradient between the water and tissues, allowing the passage to be more favorable from an energy perspective. At least one study also showed that an increased calcium concentration also resulted in higher calcification rates in Galaxea fascicularis. This is one reason I try to maintain at least NSW values of both of these or higher for both of these.

 

That said, levels that are too high definitely have an effect, as many have found anecdotally. High calcium inhibits reactions at the cellular level, as does magnesium. I haven't seen really any studies detailing toxicity from excessive carbonate/bicarbonate--though anecdotally through many instances, there is an upper limit.

[urbaneks]

IMO stability is the key to success. If you run your Cal at 425 and keep it there, the animals have a consistent environment in which to build from. In terms of importance for stability, I would rank Alk first, Cal 2nd and Magnesium 3rd. Most corals can tolerate small swings in Cal and large swings in Mag but Alk swings cause big issues. There is a current thread here on NR talking about a birdsnest coral RTN'ing. I'd be willing to bet money that the cause of the RTN event was a big swing in Alk. Talking this back to your gas/car analogy, when it comes to your big 3 parameters you want to keep the tank full. In my tank, I use a dosing pump that pumps Alk into the tank every 2nd hour. If I test my Alk before the dose and after the dose, my alk never swings more than .05dKH at any given time. I do the same thing for Cal, and Mag is dosed only 3 times a day since the overall amount is so small.

 

Hope this helps.

[Steensj2004]

The concentration actually does make a difference. In natural seawater, calcification is typically carbonate-limited. So a higher carbonate concentration can make a difference in growth, as many studies have shown. A greater concentration also increases the gradient between the water and tissues, allowing the passage to be more favorable from an energy perspective. At least one study also showed that an increased calcium concentration also resulted in higher calcification rates in Galaxea fascicularis. This is one reason I try to maintain at least NSW values of both of these or higher for both of these.

 

That said, levels that are too high definitely have an effect, as many have found anecdotally. High calcium inhibits reactions at the cellular level, as does magnesium. I haven't seen really any studies detailing toxicity from excessive carbonate/bicarbonate--though anecdotally through many instances, there is an upper limit.

IMO stability is the key to success. If you run your Cal at 425 and keep it there, the animals have a consistent environment in which to build from. In terms of importance for stability, I would rank Alk first, Cal 2nd and Magnesium 3rd. Most corals can tolerate small swings in Cal and large swings in Mag but Alk swings cause big issues. There is a current thread here on NR talking about a birdsnest coral RTN'ing. I'd be willing to bet money that the cause of the RTN event was a big swing in Alk. Talking this back to your gas/car analogy, when it comes to your big 3 parameters you want to keep the tank full. In my tank, I use a dosing pump that pumps Alk into the tank every 2nd hour. If I test my Alk before the dose and after the dose, my alk never swings more than .05dKH at any given time. I do the same thing for Cal, and Mag is dosed only 3 times a day since the overall amount is so small.

 

Hope this helps.

 

Ok, exactly what I was looking for. I was under the impression the levels directly effected reaction and growth but I wasn't sure. What would you constitute as a big swing? For example my calcium might drop 5-10ppm between doses, Alk and mag are pretty steady.

[urbaneks]

Ok, exactly what I was looking for. I was under the impression the levels directly effected reaction and growth but I wasn't sure. What would you constitute as a big swing? For example my calcium might drop 5-10ppm between doses, Alk and mag are pretty steady.

 

This depends on the types of coral you want to keep. If you are keeping softies, you can have larger swings (25ppm), if you are keeping LPS then your current swings are most likely okay. If you are keeping SPS, I would recommend a doser which will allow you to keep your tank stable with no swings.