Calcium 1200ppm?

[Anonymous]

After a short debate with Snake he mentioned that he was able to get Calcium up to 1200ppm in a healthy saltwater system so that shot a big hole in what I thought I knew about reef tanks.

Can someone explain to me under what circumstances calcium can be dosed up to 1200ppm in a healthy reef tank (normal ALK, Magnesium & PH)?

I've looked & looked but I can't find a way. The only thing I could come up with was having suspended Calcium carbonate solids in the water column when testing the water but I doubt that's what he was referring to.

I would have continued posing in the thread but he said he wouldn't be responding in that thread again. I didn't want to disrupt the "My 5 Gallon Nano" discussion so I started a new thread.

Thanks for any info or direction
Guy

 

[Sponge_Bob]

I don't have a clear answer for you but I know that calcium bicarbonate will buffer your water to about 8.2. So even if you over dose it, it will stay at that value. But your KH will be pretty high if you have 1200ppm of calcium in there. Maybe, like you said, some of his calcium might be chelated, but even then, it would still affect the Alk AFAIK. If you want a more clear answer on this, I can do some research if it really means so much to you. Just say you want it and I will find you the answer.

 

[Anonymous]

What test kit is accurate at the level?

Louey

 

[Amphiprionocellaris]

Hmm...calcium is already at supersaturation in saltwater (calcium carbonate is totally soluble, so the only thing keeping the reefs together is the fact that no more CaCO3 can dissolve), and the precipitation level (all other things normal) is about 520 ppm (give or take, depending on pH and temperature). My first guess would be a faulty test kit. Having solid CaCO3 in the water might be the ticket. My undertanding of the calcium titration is a little fuzzy, but what might be happening is that solid CaCO3 is dissolving to replace neutralized calcium ions. This would take up calcium titrant and raise the "level," but the tank's water is likely not that high.
Other than that, I have no idea how one would come across a Ca level of more than 600.

 

[Anonymous]

Other than that, I have no idea how one would come across a Ca level of more than 600.

Just some history for you, this started because I questioned Skylab1's tested parameters of :

Ca - 650ppm
ALK - 4.0Meq/l
PH - 8.4

I didn't think those levels were possible. That's when Snake mentioned some way of getting up to 1200ppm Ca. That totally blew away all I have ever heard of Calcium parameters.

I'm not a chemist so I can't say "that doesn't ring true" so I thought I'd just ask how it's possible to obtain 1200ppm let alone 650. I looked at an old article by Dr. Holmes-Farley and interpolating from what he wrote I came up with an Omega level around 9 or 10 when an Omega level of 5 means precipitation of Ca is likely.

So, what can you add to tank water besides HCL to get a Ca level of 1200ppm? He was mentioning HNO3 and Carbonic Acid (dissolved CO2)but those, by definition, would lower PH to unhealthy levels in a reef tank.

There are several alternative explainations but right now the "he's full of it" is topping my list. A distant second is that I misunderstood what he meant by 1200ppm Calcium.

 

[Amphiprionocellaris]

I'm not a chemist so I can't say "that doesn't ring true" so I thought I'd just ask how it's possible to obtain 1200ppm let alone 650. I looked at an old article by Dr. Holmes-Farley and interpolating from what he wrote I came up with an Omega level around 9 or 10 when an Omega level of 5 means precipitation of Ca is likely.

I'm just a freshman chem major, but I can definitely say "that doesn't ring true." At normal pH, alkalinity, and temperature, calcium carbonate will precipitate out at less then 600 ppm (usually much less, depending on stuff like water flow). Adding stuff like nitric and carbonic acid will allow you to increase Ca concentration, but the resulting pH from those would be rather low (like around 2.6-ish). Oh, and I've got a huge solubility and equilibrium test tomorrow, so I've been reading up on stuff like this.
I don't want to start a fight, but I am a member of the Scientific Inquisition (see sig.).

 

[pwj1286]

I have been hearing about customers coming into my store and saying that their calcium levels were above 750 ppm.

When using the Salifert testing kit, they titrated the whole syringe and still no color change. Either they are retarded and do not follow directions or their is a legit reason why this is happening to some hobbist.

The question is: "Unable to follow directions or bad testing kits or something else that has not made itself known...."

1200 ppm Ca+ can not happen in salt water. I am cautious to say it can happen over 550 ppm. After that value, depending on ALK, pH, temp., the solubility of calcium will precipitate in the form of CaCO3.

http://www.advancedaquarist.com/issues/mar2002/chem.htm

some more info.
_________________
Mercedes SSK

 

[Anonymous]

>...Can someone explain to me under what circumstances calcium can be dosed up to 1200ppm in a healthy reef tank (normal ALK, Magnesium & PH)?

It probably not going to work for most of us, but if you apply a pressure of 300 PSI and chill the water temperature to 33F, you may be able to get the calcium to arond 1200 ppm at normal reef alk, mag and pH.

 

[Anonymous]

Thanks all.

My paradigm of the universe is still intact.

 

[Anonymous]

woops here's me.

As stated above these boards have many newbies reporting calcium levels very high. Additionally, I once measured calcium at 1500ppm in my 55g. So here's my take.

We don't measure carbonate (or bicarbonate) directly. But rather alk as kinda a substitute for those. To measure alk we add acid until a certain ph value is reached. Then under the assumption of normal sea water or reef tank operation we have some "feel" for carbonate/bicarbonate for our corals, corraline, clams and so on.

In my case I had kalked (very heavily) aptasia in the tank. That added calcium and OH. So alk still measured 2-2.5 meg/l and ph still pegged the scale at 8.4 or so.

But over the next few weeks calcium went down to 450ppm while alk stayed the same at 2-2.5meg/l. When I bumped up alk to 9dkh calcium remained above 400. But one week I got carried away with the baking soda and calcium dropped to 250. Ading Calcium chloride returned to calcium to 400 and now I use less baking soda.

So what I think happend with my 1500ppm calcium was alk was still high with the OH-. Then as OH was consumed calcium dropped back as more carbonate was added to the system. With no white calcium carbonate on the glass, pumps and so on.

So I find 800-1500ppm calcium believable. With normal alk values. But that should not be desirable as the carbonate/bicarbonate would probably not be at levels to support things. Hopefully the calcium would drop with a corresponding rise in carbonate/bicarbonte to support our systems. Just as happens in new setups where there is a lot of calcium carbonate dust initially in the system.

 

[Anonymous]

The source water in my father in laws aquarium had so much calcium that after a month of not testing, it tested off the scale. Not sure if it was as high as what you posted, but it was way above acceptable norms.

Despite all other factors being within great perameters, no coral could survive in the tank. Although the fish were fine, crabs good, and his snails became monsters within a couple of months before we got the problem under control. The snails grew their shells 10 times faster than normal.


But again, no coral could survive.

 

[Anonymous]

So what I think happend with my 1500ppm cascium was alk was still high with the OH-.

How does OH- stay in solution in the presence of CO2? If ALK was normal but Bicarbonate/Carbonate was low then what was it in the water that was buffering the PH?

I have a feeling you were seeing the results of Calcium carbonate solids (precipitate) affecting your Calcium test. Yes, if you add a bunch of sand to your Calcium test it will read high, that doesn't mean your actual dissolved calcium level is even high enough to be considered normal normal.

 

[Anonymous]

could be. Probably one of the ways the calcium came down.

Also could be my ph was high and I couldn't measure the increase. which would require more acid to reach the test ph. therefore alk still measured high.

Co2 is also consumed by the plant life in my systems also. So my tank has less co2 then tank with less plant life.

anyway the calcium did come down which could be the important thing. The stable parameter was not 1500 but 400. the 1500 just kinda a shock to test the stabiliby of the system.