Kalk Reactor with CO2?

BCOrchidGuy · #1 03-11-2003, 11:50 PM

how would this work? With a kalk reactor my understanding is that you want to have a power head come on a couple times a day to mix the Kalk, then let it settle. What if there was a CO2 injector and it was on a solenoid so when the power head comes on the CO2 would come on. So basically make a Ca reactor but have Kalk in it, and don't have it running 24/7 and have it fed to the sump by a drip. Does this make any sense or am I just more confused than I was before?

DJ88 · #2 03-12-2003, 02:26 AM

I think you are more confused.

With a kalk reactor you want it sealed from anything getting in.. Top off water only mixing with the Kalk..

CO2 is used in a CA reactor to drop the pH of the rector so as to break down the Ca based media.

With Kalk you don't need to drop the pH to have Ca go into solution. It is already there once you stir it.

BCOrchidGuy · #3 03-12-2003, 03:13 AM

I was hoping to get to the Alk bennifits of Kalk..... I don't really want to run both... lol...

smokinreefer · #4 03-12-2003, 05:30 AM

you do get ALK benefits from using kalk. it will maintain levels of Ca and ALK.

Delphinus · #5 03-12-2003, 03:17 PM

I thought you didn't want CO2 in contact with kalk anyways. It will just precipitate out the carbonates and once they're precipitated out they're done, so one wouldn't get a whole lot of benefit from the kalk. That's why a kalk reactor is sealed -- it's to prevent any unnecessary contact with air. Just my $0.02..

BCOrchidGuy · #6 03-12-2003, 03:56 PM

I'm so confused.

I thought the Kalk would only give me the Alk bennifits if it was being exposed to CO2 like from a moderate to heavy fish load.

I've got alot more reading to do I guess. Thanks for all the replys folks.

reefburnaby · #7 03-12-2003, 09:20 PM

Hi,

Some kalk reactors from Germany inject CO2 into kalk. It works both ways.

Ca(OH)2 + H20 <=> Ca++ + 2OH- + H20

CO2 + H20 <=> H+ + HCO3-

So

Ca(OH)2 + 2H2O + 2CO2 <=> Ca++ + (2OH- + 2H+) + 2HCO3-

So what does all that mean. Well, Ca(OH)2 or kalk, by itself adds Ca++ or ionic calcium to the solution. Also, it adds an OH- or hydroxide or pH increasing agent to the water. If we don't add anything else to the water, the OH- concentrations we get so high that we have a pH of 11 in our reef tanks. Obviously, something else happens before the pH reaches 11.

CO2 is always present in our tanks and it has a negative pH contribution (i.e. it adds H+). So, CO2's acidic properties cancels kalk's base properties. The left over component is HCO3- which is a bicarbonate...the same bicarbonate we add as a buffer in our 6 to 1 ratioed DIY buffer. This is the 6 part of the buffer...the bicarabonate part in Sodium Bicarbonate. The bicarbonate will eventually convert to carbonate since it may not be favourable (due to pH). The combination of bicarbonate and carbonate concentration is what forms our alk.

As you can see, you need some sort of CO2 for the kalk to add alk to your tank. Why does kalk cake on the surface of the kalk mix ? Well, that is what happens when there is too much CO2, but there isn't enough CO2 to convert the Calcium carbonate back to Ca++. So, it is sort of a funny boundary state.

- Victor.

smokinreefer · #8 03-12-2003, 09:30 PM

basically,
the main difference is...you can only use as much kalk water as you evaporate. if your evaporation rate is high enough that your kalk can keep up with your tanks demands, then that is all you need.

if you do not evaporate enough water, your kalk cannot keep up with your tanks demands, then you will either need to supplement the kalk with another additive, 2 part, what have you....or....

use a calcium reactor, which you can adjust/tune to meet the needs of your tank.

gotta go to work now, i'm sure someone else will chime in if you have more questions.