Getting a grasp on the big FOUR parameters

[SnowManSnow]

PART 1
:!:
Ok, so I'm learning more about Ca, Mg, Alk, and pH.. and how they relate to each other in my quest to have a more "productive" reef tank.

Ok, so...
1) First, basically, you have Ca, Mg, and Alk, that keep pH in a given range. A "target range" PH can be obtained by keeping the above 3 in the appropriate ranges correct?

2) CO2 also has an effect on PH.. The 2 (CO2 and pH) are CONversely proportunal.. the more CO2.. the LOWER the PH. Correct?

These 2 things taken into account:
pH is a derivitive of the other 3, therefore if pH is in an unaccptable range the other 3 variables should be addressed?


_______its only part one! part 2 is coming up !

 

[SnowManSnow]

OK part 2
I have been experiancing participate when I add ALK of a 2 part to my water (remember my alk is a little high right now at 6meq/L.

Would the participate be explained like this?

Calcium bicarbonate lvls in the tank are at saturation point. When I add ALK to the tank the water becomes supersaturated and parcipitates the Ca out of the column as it reaches saturation.

Correct?

 

[SnowManSnow]

Part 3

pH and Calcium bicarbonate..
1) a lower pH allows for a higher saturation point of Ca and Bicarbonate?
but..
as pH DROPS.. it kind of pulls the acceptable saturation point DOWN so that percipitate occures quicker? Thus lowering the amount of usable Ca in the system.

THEREFORE as in a Ca Reactor

CO2 is injected into the system which counteracts the dropping of the pH and drives it UP so that HIGHER saturation points can be reached with ca.
OK THIS DISAGREES with #1... what's the deal? :x

 

[MartinE]

Co2 Raises PH. Most of the rest sounds about right.

 

[Anonymous]

PART 1
:!:
Ok, so I'm learning more about Ca, Mg, Alk, and pH.. and how they relate to each other in my quest to have a more "productive" reef tank.

Ok, so...
1) First, basically, you have Ca, Mg, and Alk, that keep pH in a given range. A "target range" PH can be obtained by keeping the above 3 in the appropriate ranges correct? Yes, well it's a start anyway.

2) CO2 also has an effect on PH.. The 2 (CO2 and pH) are CONversely proportunal.. the more CO2.. the LOWER the PH. Correct? Yes

These 2 things taken into account:
pH is affected by the other 3, therefore if pH is in an unaccptable range the other 3 variables should be addressed? Yes

 

[Anonymous]

as in a Ca Reactor

CO2 is injected into the system which counteracts the dropping of the pH and drives it UP so that HIGHER saturation points can be reached with ca.
OK THIS DISAGREES with #1... what's the deal? :x

My understanding is that CO2 is injected into a CA reactor in order to lower the Ph, because at the lower Ph value, the reactor media can begin to dissolve and enter the solution.

 

[Anonymous]

Co2 LOWERS PH. Most of the rest sounds about right.

There... fixed that for you.


Could you post some numbers regarding your specific situation?

 

[kevindub]

CO2 is used to lower the pH in a reactor to dissolve the media. When it does this it makes carbonate which increases alkanity. If you add a lot of Co2, you will lower your pH but increase your alkanity and calcium levels, so when you add two part solutions, it might precipitate out since the water is already saturated.

 

[Anonymous]

Co2 Raises PH. Most of the rest sounds about right.

No. That is false. Carbon dioxide dissolves in water to make carbonic acid, a weak diprotic acid:

CO2 + H2O ⇌ H2CO3

The relevant dissociation is loss of the first proton, with an associated pKa1 = 6.37 (meaning half is dissociated at pH 6.37). Pure water exposed to CO2 in the atmosphere will therefore be slightly acidic.

 

[Anonymous]

PART 1
:!:
Ok, so I'm learning more about Ca, Mg, Alk, and pH..

The first three have only indirect effects upon the pH. The "alkalinity" is basically a measure of the buffering capacity of seawater, i.e., its ability to keep the pH from deviating from a natural value of about 8.1. Ca(CO3) is insoluble, so if you overdo the calcium, you deplete buffering capacity, and can then experience problems maintaining pH. It is more common for it to go down rather than up (your animals expire CO2, which lowers the pH), but in principle it could also do the opposite more readily.