Calcium Reactors Vs. Kalkwasser: Pros/Cons

[cgill311]

Alan tried to tell me once, but I didn't quite understand and after seeing Mike selling 2 calcium reactors, it got me thinking. So here are my questions:

1) How exactly does a calcium reactor work?
2) Pros/Cons of calcium reactors vs. kalkwasser dosing

Please enlighten me as to why a person would want one versus the other. I'm dosing kalkwasser via the homemade contraption Sammy posted about several months ago. It does well keeping the pH up. I don't monitor calcium levels, so maybe someone could comment about that too. :huhsign:

 

[siege]

Er, well, I know that a kalkwasser drip isn't good for getting calcium UP, as much as it is for keeping it there. I also am made to understand that calcium reactors are the best bet for a good natural balance, but are terribly expensive and fairly complicated, since, IIRC, a calcium reactor also neccesitates CO2 to complete the balance.

 

[FutureInterest]

From my limited understanding... people that use calc reactors over simply dosing kalk in top off water do so out of "necessity". Usually the calc reactor folk have such a high calcium demand in their stony dominated reefs that dosing kalk cannot keep up with the demand. As such, if you can maintain your alk and calcium with kalk dosing then by all means keep using it, if you can't and find that you have to dose often with 2 part then think about spending your kid's bike money on a calc reactor.

 

[cgill311]

So how does a calcium reactor actually work? I'm not sure where the CO2 comes in.

 

[FutureInterest]

Yah you're the chem brain . Anyways, the CO2 is dispensed into the reaction chamber, it thereby lowers the ph in there which as you know will then allow the CaCO3 media to dissolve into solution. At our typical reef ph of ~8.2, you get very little to no actual buffering from argonite based sands and rocks... which is why the CO2 is used in the reaction chamber. You're going to need a ph of at least 7.7 according to Randy to get the media to dissolve and some people go as low as 6.5.

Here's a good article, good ole reefkeeping magazine:

 

[mufret]

Both kalwasser and a calcium reactor are going to add calcium to your system. Everything else being balanced, the kalwasser will also help maintain your PH while the calcium reactor will help in maintaining your alkalinity. The reactor can also be used to dose magnesium. The calcium reactor setup is actually pretty simple. It uses CO2 to lower the PH in the reactor which causes the media to become soluable. Cost can be an issue with a reactor but tnly thing that needed is a reactor and CO2 tank w/ regulator. Having a PH monitor/controller is a plus. Reactor are not just for SPS tanks. Many of the animals we keep in our systems use calcium. Clams and LPS also have high calcium demands and can some times strain smaller setups. I happen to use both and have found it much easier to maintain the alkalinity, PH and calcium levels in my tanks by doing that. I also add magnesium to my reactors to help with that as well.

 

[broreefr]

Calcium Reactors use ARM which is basically fine coral shells in a closed enviroment and CO2 is slowly added as the system water is forced through this media. The CO2 slowly dissolves the media thereby releasing calcium into the system. CO2 aside, its a pretty natural way to suplement calcium to the system.

Kalkwasser is the German word for limewater, it is slowly dosed into the fresh RODI TOP-OFF water to additionally maintain levels added in this topoff.

They really cant be compared head to head because they really work together to maintain suitable calcium for corals that grow there own hard skeletons

 

[cgill311]

dawgdude;38538 wrote: Says the chemical engr..............

Touche!

So basically the only difference is the anion you add. Both add Ca+2 cations to increase calcium levels. The kalkwasser will add 2(OH)-1 ions to increase pH versus 2(HCO3)-1 by calc reator which adds additional buffering capacity.

Carbon dioxide dissolved in water will form carbonic acid:
CO2 + H2O --> H2CO3

This will react with the calcium carbonate forming aqueous calcium bicarbonate.
H2CO3 + CaCO3 --> Ca(HCO3)2 --> Ca+2 + 2(HCO3)-1

 

[cgill311]

mufret;38547 wrote: I happen to use both and have found it much easier to maintain the alkalinity, PH and calcium levels in my tanks by doing that. I also add magnesium to my reactors to help with that as well.

Mike, what ratios do you run each at? I'm assuming kalkwasser via ATO and then just setting the calcium reactor at a constant rate?

What ratio of MgCO3 to CaCO3 do you run in the calcium reactor?

 

[mufret]

CGill311;38556 wrote: Mike, what ratios do you run each at? I'm assuming kalkwasser via ATO and then just setting the calcium reactor at a constant rate?

That's correct.

CGill311;38556 wrote: What ratio of MgCO3 to CaCO3 do you run in the calcium reactor?

10/90% mix of Dolomite and ARM. There are, now, other magnesium supplements that you can add such as ZeoMag.

 

[kwl1763]

The CO2 is only for pH purposes to melt the media. I'm sure the reaction above does happen but the only reason Co2 is used is to dissolve and free up the ions in the media not to react with them and create something new. I mean I guess that is technically a reaction but I'm sure if we injected vinegar in there and lowered the pH the media would also melt. A calcium reactor is an amazingly simply device. Put some calcium cabonate media in there. Lower the pH to melt the media by injecting a small amount of CO2. The drip the saturated calcium carbonate solution back into the tank. That's all it does.

They both add balanced cabonate (buffer) and calcium but the above is correct and opver very liong periods of time people only running calcium reactors tend to have alk slightly elevated over balanced levels and people running purely kalk have the opposite. These effects are very small though and with normal water changes are non issues in either case.

So back to the pros and cons.

Calcium Reactor:

Pros -
1)Super easy once dialed in. Zero time sppent maintaing for literally months
2)Very difficult to nuke the tank. If to much CO2 is introduced it might melt the media and clog stuff but the drip rate is only so much and that can't increase. If you have the output above the water and a bunch of CO2 got dumped (valve malfunction or whatever, I've never had it happen in 10 years) it would just get blown off through the output.
3)You can easlily add magnesium to the media
4) No mxiing, no mess, no worrying about how long it sits, etc.

Cons:
1) Intially it's expensive. Your going to drop around $500 on equipment
2) pH of output is low so if you have a low pH in your tank it certainly won't help!
3) The dial in period does take a few days to a couple weeks

Kalk:

Pros:

1) Super Cheap
2) Not difficult, just mix it up
3) High pH can help some if your pH is low

Cons
1) Real easy to nuke tank if overdosed. Search for kalk nuke on RC! Then search for calcium reactor nuke. Nuff said
2) Loses potency when exposed to air so at least weekly you have to add/mix
3) Is caustic and you need to be careful when handleing or breathing around it.
4) Leaves nasty residue on container it's in (Minor but still)

Now the last 3 cons are most;y handled if you use a kalk reactor but that takes away pro number 1 which is the biggest.

I personally prefer a calcium reactor only (I've used one alone for almost 10 years now) just due to the fact that it's easier to mess something up with kalk. The only way I would do kalk is through something like a liter meter where there was no way it could dump to much in. A calcium reactor is truly aset and forget. Anything that saves me time I'm all for!

Truly the "best" chemically would be to run both as others have suggested.