Chem Quiz: Which has the highest pH boost?

[johnwwalkeriii]

E & C. I use randy/miami’s 3 part with the sodium hydroxide. Couldn’t be happier.

 

[Miami Reef]

ANSWER

Which one has the highest pH boost when raising alkalinity from 7–8 dKH?

A) All For Reef
B) Calcium reactor
C) Kalkwasser
D) Baking soda (sodium bicarbonate)
E) Sodium hydroxide
F) Soda ash (sodium carbonate)

Slightly trick question: both kalkwasser (calcium hydroxide, Ca(OH)₂) and lye (sodium hydroxide, NaOH) are composed of hydroxide. The sodium or calcium in either compound has no effect on the pH.

Even though you’ll require a MUCH higher volume of kalkwasser compared to sodium hydroxide (NaOH), the key factor is how much hydroxide actually dissolves. Calcium hydroxide (kalkwasser) is very poorly soluble in water.

When you raise alkalinity by the same amount with either chemical, you’ll end up requiring the same number of hydroxide ions, resulting in the same pH increase.

It’s a common misconception that kalkwasser is the strongest pH-boosting additive. While it’s certainly among the highest, it isn’t inherently stronger than its sodium-based counterpart when dosing equal units of alkalinity in the same time-period.

 

[shollenberger]

I’m going to lay out a list of common alkalinity dosing additives. Which one has the highest pH boost when raising alkalinity from 7–8 dKH?

A) All For Reef
B) Calcium reactor
C) Kalkwasser
D) Baking soda (sodium bicarbonate)
E) Sodium hydroxide
F) Soda ash (sodium carbonate)

E. NaOH is a strong base. Most -OH released which changes the pH the greatest.

 

[EnterName]

Disclaimer: I'm not a chemist, so I'm just writing this to participate in the little quiz, not to claim I know the answer. If you plan on increasing alkalinity or pH please do not rely on the numbers and calculations here.

First: Calcium reactors add CO2 to dissolve CaCO3 so they effectively even reduce pH. NaHCO3 increases CO2 levels as well, which is why it is nearly pH neutral shortly after being added. All for Reef contains simply various compounds not all of which are contributing too much to alkalinity or pH so I think it's between Na2CO3 and NaHCO3.

For the residual options:

1mg/L CaCO3 (~ 17.857 dKH) should be equivalent to:

• 0.560mg/L (CaO)
• 0.741mg/L (Ca(OH)2)
• 0.799mg/L (NaOH)
• 1.059mg/L (Na2CO3, assuming anhydrous form)
• 1.679mg/L (NaHCO3)

I spare you the calculations to get to these numbers.

So you can add approx.:

• 10.000mg/L (CaO)
• 13.232mg/L (Ca(OH)2)
• 14.268mg/L (NaOH)
• 18.911mg/L (Na2CO3)
• 29.982mg/L (NaHCO3)

to increase by 1 dKH (from 7 to 8).

CaO in water reacts as follows: CaO + H2O -> Ca(OH)2 so it adds 2 OH-.
NaOH is simply one OH-. So based on the molar masses of CaO and NaOH you can calculate:
10mg/L CaO produces the same amount of OH- than 14.268mg/L NaOH. So Kalkwasser is the same as NaOH regarding the pH boost in this case.

My Answer:

CaO, Ca(OH)2, Kalkwasser and NaOH are all equivalent regarding pH when only increasing by 1dKH and give the largest boost.

Edit: All these calculations assume the used chemicals are 100% pure and every molecule reacts accordingly to the theory instead of undergoing different reactions with substances in the tank.

 

[EnterName]

Disclaimer: I'm not a chemist, so I'm just writing this to participate in the little quiz, not to claim I know the answer.

First: Calcium reactors add CO2 to dissolve CaCO3 so they effectively even reduce pH. NaHCO3 increases CO2 levels as well, which is why it is nearly pH neutral shortly after being added. All for Reef contains simply various compounds not all of which are contributing too much to alkalinity or pH so I think it's between Na2CO3 and NaHCO3.

For the residual options:

1mg/L CaCO3 (~ 17.857 dKH) should be equivalent to:

• 0.560mg/L (CaO)
• 0.741mg/L (Ca(OH)2)
• 0.799mg/L (NaOH)
• 1.059mg/L (Na2CO3, assuming anhydrous form)
• 1.679mg/L (NaHCO3)

I spare you the calculations to get to these numbers.

So you can add approx.:

• 10.000mg/L (CaO)
• 13.232mg/L (Ca(OH)2)
• 14.268mg/L (NaOH)
• 29.982mg/L (NaHCO3)
• 18.911mg/L (Na2CO3)

to increase by 1 dKH (from 7 to 8).

CaO in water reacts as follows: CaO + H2O -> Ca(OH)2 so it adds 2 OH-.
NaOH is simply one OH-. So based on the molar masses of CaO and NaOH you can calculate:
10mg/L CaO produces the same amount of OH- than 14.268mg/L NaOH. So Kalkwasser is the same as NaOH regarding the pH boost in this case.

My Answer:

CaO, Ca(OH)2 (Kalkwasser) and NaOH are equivalent regarding pH when only increasing by 1dKH and give the largest boost.

Ah ****, I took so long to calculate and write my answer that the solution has been posted before I was ready :(