Can you overdose calcium?

[oz]

If so, what are the effects of that? what parameters will spike as a result?

 

[ralph atl]

alk & ph will crash

 

[glxtrix]

yeah you'll either have a snow storm or your alk will dip very low. It's rare for both to go down together....esp if one or the other goes too high.

 

[schwaggs]

And you will create a buildup of calcium on your heaters and inside your pumps/powerheads. The buildup will eventually stop your pumps...

 

[george]

Some calcium sources are easier to overdose than others. Usually because they also affect alkalinity or pH, such as Kalkwasser.

 

[oz]

I have a dual chamber MRC but still dialing it in. small media so I have the ph in the first chamber around 6.7. I have a constant drip as output into my sump.

Question: How do I know it is adding calcium to my tank? How do I know the media is breaking down?

 

[tdwyatt]

ChrisOzment;225338 wrote: I have a dual chamber MRC but still dialing it in. small media so I have the ph in the first chamber around 6.7. I have a constant drip as output into my sump.

Question: How do I know it is adding calcium to my tank? How do I know the media is breaking down?

So you are NOT delivering just calcium to the tank, ie, that you are not dosing just the calcium of a two part supplement system, or dumping in spoons of calcium chloride.

When a calcium reactor dissolves the media, it makes eqimolar amounts of both calcium and alkalinity (as circulating bicarbonate), which then goes through equilibrium distribution (Le Chatlier's) to make ~90% bicarbonate, 10% carbonate. If the calcium and alk in the tank were balanced to start with, then you will not be changing the proportion of one to the other by addition of reactor effluent. The only time you will have issues is if you add a single part of this mix through the use of one part of a two part additive. Whenever you add extra calcium or alk, it will increase its concentration up to a certain level, then cause precipitation of both calcium and bicarbonate/carbonate to form calcium carbonate. this reduces equal amounts of both ions on a molar basis, so your ASW ends up with a defecit of one part and the exceseses of whatever you used as the other part. Think of bowl of marbles in which you have red (calcium) and blue(bicarbonate) marbles filled to the brim. We could consider this bowl filled to its maximum, or that it is holding all the marbles it can hold, so much so that they are piled up above the rim and the bowl is actually holding more than we would initially have anticipated based on the size of the bowl. In terms of solubility, we would say that this bowl is supersaturated with respect of red to blue marbles; the bowl is keeping marbles in beyond what we would calculate as its maximum ability to hold marbles (calcium and alkalinity in solution). If we add one more marble, marbles will spill out of the bowl (precipitate). If we make our marbles magnetic, so that red marbles will only stick to blue marbles, then for every red marble that falls out, one blue marble will fall out. This means that even if we pour in a hanfull of red marblees, then red and blue marbles will fall out, not just red marbles. We will reduce the concentration of blue marbles by the number of red marbles that fall out. This is what happens when we have precipatory events from supersaturation of calcium with respect to alkalinity. If we throw in a few PPM of calcium, alkalinity will drop by the number of calcium carbonate molecules that precipitate out, as will the bicarbonate ions (the red and blue stick together). This is why adding excessese of one or the other part of two part additive causees disruptioin in both ions.

When adding CO2 to seawater, it acidifies the solution to allow dissolution of calcium carbonate (the argonite) yielding equal molar amounts of both calcium and alkalinity. Because this occurs, all we have to measure is either calcium OR alkalinity IN OUR EFFLUENT SOLUTIONS TO KNOW WHAT WE ARE DELIVERING. If you measure alkalinity in the effluent, a high alk tells us that we are delivering an equimolar amount of calcium ions as well. Over time, the aragonite medium will disolve enough for you to see that it is gone...

http://www.atlantareefclub.org/forums/attachment.php?attachmentid=13465&stc=1&d=1223327812" alt="" />
<span style="font-size: 11px;">MRC CR6 at 5 months @ pH range 6.5-6.6</span>

If you have a good population of hermatypic organisms in a reasonably sized (180 USG tank plus 50 USG sump) system, you will have plenty of room to dial in your reactor. By starting at a range of 6.6-6.7 and working your way to a point where the system does not see downward trends for calcium and alk, you will not be able to OD the tank on calcium so long as it is in balance with alk. If you do get a bit high on hermatypic supplements, the tank will precipitate out the excesses (wasteful, but safe for the corals). We call this precipitate calcareous sand (or parrotfish poop).

HTH
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[dannybradley]

Tom- what an excellent asset you are to this hobby. Even working for the sister company of My Reef Creations, I certainly couldn't have come close to saying it better, myself.

 

[oz]

Yes - great analogy as well.