Adding CO2 into Kalkwasser

[jaefei]

Dear Mr.Randy,

If I want to make my PH stable,until how many PH I must reach in my kalkwasser if I add CO2 before add kalkwasser into my tank?
adding CO2 into kalkwasser change alkalinity or not ?

Best regards,
Jeffry

[Randy Holmes-Farley]

Adding CO2 into limewater (kalkwasser) is a big mistake. You'll precipitate all of the calcium and alkalinity from the water, and be left with calcium carbonate sand.

If the aquarium pH is too high and you want to use CO2, you must add it to the aquarium, not the limewtaer itself.

I discuss the reaction between CO2 and limewater in this article:

The Degradation of Limewater (Kalkwasser) in Air
http://reefkeeping.com/issues/2003-05/rhf/feature/index.htm

[thackray]

Jeffry,

I added an air stone with air pump to my kalkwasser (limewater) only tank and reduced the pH a few tenths of a point. If you dose your kalkwaser at night and run the air stone/air pump during the day this will help regulate your pH. The air stone may help clean the surface of the water - it did so on my tank.

Marine Depot can sell you a set up to introduce CO2 from a storage tank in your tank water using a pH controller and a "reactor" that just mixes the CO2 and tank water. The sales guys there can help you.

Philip Thackray

[thackray]

Jeffry,

After I read my post I realized that it might be confusing. The air stone is in the main display tank. I feed my system with only kalkwasser.

Phil

[jaefei]

I don't have ph controller. So,how much CO2 I must add into my tank to change 0.3 ph( from 8.5 to 8.2)...?

[JoeMack]

Originally posted by Randy Holmes-Farley
Adding CO2 into limewater (kalkwasser) is a big mistake. You'll precipitate all of the calcium and alkalinity from the water, and be left with calcium carbonate sand.


I want to try this :)

[JoeMack]

so far some of the kalk sunk to the bottom in clumps. But when empyed it crushed like kalk. Maybe I added too much to disolve? I did the experement again and am carbonating the kalk. I know I'm strange. Its all Randys fault :)

[thackray]

Try the air stone/air pump. I't may not do enough but it will not cause any problems. It may take a day or so to notice any effect.

I would not inject CO2 gas into the tank without some type of control.

[Habib]

Originally posted by jaefei
I don't have ph controller. So,how much CO2 I must add into my tank to change 0.3 ph( from 8.5 to 8.2)...?

Your tank also produces CO2.

To start with I would say for each gram of added calcium hydroxide I would add 300 ml of CO2 gas to the tank and then adjust it depending on what the pH in the tank does.

Dosage of CO2 must be gradual and at the same time as the kalkwasser dosage otherwise the pH might drop a lot.




So that others can check the reasoning and the math how I came up with the 300 ml CO2 per gram of calcium hydroxide:

The tank produces CO2 and there is also CO2 input by aeration.

So just want per calcium hydroxide molecule one bicarbonate and one cabonate produced.

So one mole of CO2 per mole Ca(OH)2

1 gram Ca(OH)2 = 1/74 = 0.0135 moles

0.0135 moles of gas = 0.0135 x 22.4 (liter/mole) = 0.302 liter = 300 ml.

[Randy Holmes-Farley]

Joe:

so far some of the kalk sunk to the bottom in clumps. But when empyed it crushed like kalk. Maybe I added too much to disolve? I did the experement again and am carbonating the kalk. I know I'm strange. Its all Randys fault

I show the effects of adding CO2 (via air additions with an airstone) to limewater in the graph below:

http://reefkeeping.com/issues/2003-05/rhf/feature/images/image006.gif

[Randy Holmes-Farley]

Since your experience has recently jumped from nil to 13 years, I'll have to agree with your math, Habib. :)

[jaefei]

okey.thanks you.

Can I use Calcium gluconate to raise calcium level in the tank ? is it safe for coral ?

[jaefei]

Anthony Calfo recomend Calcium gluconate to make coraline algae healtier. What the special of calcium gluconate until he recomend it ?

[Randy Holmes-Farley]

i presume that you mean Seachem's calcium polygluconate? I am not a fan of it as I do not understand what happens to all that polygluconate, nor even whether it adds any alkalinity or not.

[jaefei]

I want to try this gluconate.
1. is it same Calcium Gluconate and Calcium Polygluconate ?
2. I want to buy it at chemical store. Is it safe ?
3. how about dose it if it is a powder ?

[Randy Holmes-Farley]

No. gluconate and polygluconate are not necessarily the same. I'm not sure which one you are referring to, except that I know that Seachem sells calcium polygluconate:

http://www.seachem.com/products/product_pages/ReefCalcium.html

FWIW, folks recommending it may also not know that there is a difference between gluconate and polygluconate, so be careful taking such advice as to exactly what to use.

Here's a web site selling calcium gluconate for people to consume:

http://www.rxlist.com/cgi/generic3/calciumgluc.htm

and here for tissue culture:

http://www.rpicorp.com/index.php?cat=773&id=802&t=biochem