Calcium Levels

[1234-fishy-freind]

I have been wondering about calcium levels over the last couple of days.

I know it should be kept between about 380 - 430 but why?

Making sure it isnt low is abviuos but why cant they go to high?

Just a general wondering.

 

[kj23502]

ooo good question!!!

I'll be watching

 

[Crazy fishes]

What a question that should really get a discussion going. Let me kick things off then. There is no rule that says calcium levels can not go above the upper end of the range you quoted. I was running my calcium at 620ppm for a while; not intentionally but it just went that high after I inadvertly dosed the tank with calcium suppliments. It has no directly harmful effects on the livestock you keep, in fact my Euphyllia Spp really seemed to like it (this was manifest by them growing frantically). However running a high calcium will consume the bicarbonate and carbonates A LOT faster; I had little flakes of calcium carbonate floating round my tank for a few weeks. As these are major determinants of pH it may cause the pH to fall, in some cases rapidly, which is harmful to all concerned.

If you run the calcium too low i.e. lower than the level you quoted then this does have adverse affects on water chemistry and coral growth. All corals, particularly LPS and SPS but also soft corals, use calcium to make their skeleton and therefore if the levels are low in the water they have limited supplies to make more skeleton and hence grow. Water chemistry relates to the above mentioned interactions calcium has with the important buffers, carbonates and bicarbonates.

The range you quote is taken from the data found with natural sea water 380ppm is the usual value quoted although as with salinity it varies around the great ocean.

I hope this helps as a little introduction to a massive topic and I am sure others will add their views


Regards

 

[ox5477]

Well I have heard one here... like with the carbonate... you wanna keep it a little on the higher end to ensure the corals have the proper amount of resources. I try to keep my calcium around 450 and have been trying to buffer my alkalinity up to 9 or 10. These are good values to keep in any type of tank with corals, whether softies, lps or sps. Obv, with sps, these minerals are used up much faster and hence alot of tanks with lots of sps use reactors to help keep these up. But for a softie tank, these levels can be kept pretty contant with normal water changes... maybe only a small amount of buffering here or there.

Ox

 

[SkiFletch]

Yeah, CF hits on the main point here. Seawater chemistry is all about balance between calcium, alkalinity, and magnesium (hereafter "the big 3"). If the big 3 are in balance, things are good, even if that balance is high. As Ox mentioned, calcium of 450, alk of 9 and a magnesium of say 1330 is a nice balanced chemistry. Each value is higher than that in NSW, but because they are a similar percentage higher, the chemistry is still in balance.

What CF mentioned with really high calcium and low alk (probably also low to average mg) is very unstable chemistry. As CF saw, you get precipitation reactions pulling mostly insoluble calcium carbonate out of the water column and making it into small solids. This change can happen RAPIDLY, crashing the pH and making the water milky white. This is of course bad but not really the end of the world. Aeration and time will commonly fix cloudy water from a crash due to an overdose of calcium or alkalinity.

The one thing I haven't discussed yet is Magnesium. It's role in seawater chemistry is complex, playing a part in many processes. Without going into the details and trying to keep this understandable to those without a chemistry PhD, Magnesium serves to keep seawater chemistry more stable. When mag is high, precipitation reactions are less likely to occur, AND calcification (making coral skeleton) is boosted. When mag is low, obviously the opposite is true.

 

[1234-fishy-freind]

Thankd for that info guys, you can never know enough in my oppinion.