Reef Chemistry Question of the Day #265 Potency of Alkalinity Supplements

[Randy Holmes-Farley]

Reef Chemistry Question of the Day #265

Which of the following alkalinity supplements adds the most alkalinity to an aquarium per gram of dry additive used?

A. Sodium hydroxide
B. Calcium hydroxide
C. Sodium bicarbonate
D. Sodium carbonate

Good Luck!























.

 

[dimo]

My pick is D.

 

[GMay]

A. Sodium Hydroxide

 

[Sabellafella]

Kalkwasser maybe? B

 

[Randy Holmes-Farley]

I like it when there is a nice spread in the responses.

 

[AKReef]

My vote is D.

 

[Potatohead]

It's A. Final answer.

 

[chipmunkofdoom2]

A. Sodium Hydroxide.

The devil is in the details.. pay attention to the wording of the question.

 

[Randy Holmes-Farley]

FWIW, I changed the question to say gram of dry additive so folks weren't making assumptions about typical concentrations in liquid products.

 

[CNDReef]

A

 

[Luno]

C, only because it's the alk in Randy's recipe lol

 

[hafer12]

Bicarbonate, C!

 

[wranodj]

D

 

[Sleepydoc]

What's your definition of Alkalinity? In reef tanks, we frequently refer to 'alkalinity' as the bicarbonate concentration; essentially its buffering capacity.

If you are asking what will raise the pH the most per gram it would be A. In terms of our typical reef definition, C

 

[Hans-Werner]

Alkalinity should be buffering capacity. I go with B because calcium is a divalent cation and it has two hydroxide ions.
1 g of Ca(OH)2 is 13,5 mmol and neutralizes 27 mmol of acid while 1 g of NaOH is 25 mmol and neutralizes only 25 mmol of acid.

 

[Genomecop]

What do I win?

 

[Chuk]

Bicarbonate by weight
C

 

[Christoph]

B

capacity for 2 H+ s on low molecular weight

 

[JimWelsh]

What's your definition of Alkalinity?

The exact definition of total alkalinity (Dickson, 1981) is:
TA = [HCO3-]+2[CO3--]+[B(OH)4]+[OH-]+[HPO4--]+2[PO4---]+[SiO(OH)3-]+[HS-]+[NH3]-[H+]-[HSO4-]-[HF]-[H3PO4]

 

[Ferrell]

I’m gonna go with A. Possibly C??? Nope gonna stick with A. A it is