Calcium Levels And Growth Rates

[crlkeep]

How does the level of calcium directly affect the growth rates in corals?

Any one ever done any testing or experimenting to find out. Well for 2 week now, I have been using a measuring stick (small and plastic) to measure the growth rate of my Brown Staghorn, and get 2 mm every 4-5 days. This is at 420 ppm Ca. with 800 Watts of VHO flourescent lighting. My carbonate hardness is steady at 11 dKh. Magnesium is at 1280 ppm. I am going to raise the Calcium up to 450 ppm over the next few weeks, and then monitor the growth once it has stabilized at 450 ppm. No other adjustments will be made except for a 15% bi-weekly water change. If you are interested in the results, or more details, let me know.

[Andy Hipkiss]

Chuck,

In the scientific world, coral growth is reckoned to be alkalinity limited NOT calcium. This kinda makes sense since there are about 9 or more (milli) equivalents of calcium per litre in NSW vs only about 2.5 of alkalinity. Bear in mind that coral skeleton is basically a 1 to 1 ratio of Ca to carbonate so really I believe that worrying about Ca is not particularly relevent.

FWIW

[ukreefer]

Hi Guys
I would have to agree with Andy here, since I have been having low Alkalinity porblems I have seen very little coral growth but my calcium levels are ok.

Regards Dan

[crlkeep]

I have read research papers that say that calcium uptake on coral reefs is measured by alkalinity depletion.

This was not the topic of the paper, but was mentioned. Anyone got any idea exactly how this depletion is measured. Since the parameters of coral reefs don't vary much. How do they know how much alkalinity has actually been used up? ;)

[Andy Hipkiss]

Chuck,

The pH and alkalinity of seawater is measured both upstream of the corals and downstream. The difference is plugged into an equation and a value is then achieved. There is much doubt on whether the alkalinity anomaly technique as it is normally called is particularly accurate however.

IIRC the technique was developed by S. V. Smith and a search on the above terms might give you more info.

FWIW

[crlkeep]

Thanks Andy.

I will do a search later on, and post any relevant info I may find.