Question about Kalkwasser and Vinegar

[Wrasse-cal]

Ok, one last question. What’s your ph?

Oh wait. Your alkaline is 8.5-8.6? Or is that your ph?

pH is 8.3-8.4

 

[theMeat]

dKH of 8.5 is not bad, if steady. Although on low side. I usually shot for 10 to give some wiggle room up or down.
A few things on my years of kalk dosing....
Every year, around the same time of year I see my alkaline go down. I use baking soda to raise it once or twice and then it seems to be good again. Not really sure why this happens, or why it only happens once a year around the same time. But do notice it’s always when my magnesium is also on the low side. Here’s a calculator
http://reef.diesyst.com/chemcalc/chemcalc.html
Dosing vinegar will effect your ph, and you’ll also be effectively carbon dosing. Which isn’t necessarily a bad thing, if you keep that dosing regular. I always looked at dosing vinegar in kalk as a way of upping the max amount of kalk I could dose per gallon.
You could also use a kh supplement, like one half of a two part solution, and will say that when your alk goes up your cal will go down, and vise verse, and when magnesium is low it’s hard to keep either stable.

Oh, and the slurry at bottom of container is normal/typical , even if below saturation point. I usually clean it out every 3-4 mos or so.

 

[Dan_P]

I can't find an answer to these exact questions:

I understand adding vinegar to kalkwasser will allow more Calcium ions into the solution, which will increase the Calcium saturation of the solution, meaning less saturated kalkwasser is needed to maintain Calcium.

1. Is there a sizable effect on kalkwasser pH when adding vinegar? I frankly like the pH raising effect of kalkwasser. How significant is the pH drop when dosing 25ml of 5% Acetic Acid per liter of saturated kalkwasser?

2. I understand about the increased Calcium ion saturation, when adding vinegar, but what effect does dosing vinegar have on the KH of the kalkwasser? Does it also increase it proportionally to the Calcium?

Thanks @JimWelsh for the homework assignment :-)

Since we do not know how much excess solid is in the reservoir, I would start with Jim’s analysis, i.e., pH of clear solution would drop a bit because 25 mL of vinegar would neutralize about half the alkalinity. And upon addition of vinegar, the kalkwasser solution is no longer saturated and more of the solid kalkwasser will dissolve, keeping pH high. What you will be dosing is a solution with a higher ratio of calcium to alkalinity, though over time, the acetate will be metabolized to give you back the neutralized alkalinity.

I think the answer to question 2 is that the KH of the dosed solution goes up because you now have kalkwasser plus calcium acetate.

What do you think @JimWelsh ? B+?

 

[JimWelsh]

What you will be dosing is a solution with a higher ratio of calcium to alkalinity, though over time, the acetate will be metabolized to give you back the neutralized alkalinity.

I think the answer to question 2 is that the KH of the dosed solution goes up because you now have kalkwasser plus calcium acetate.

I agree with both of these statements, although, as you point out, the acetate doesn't "count" in terms of alkalinity until after it gets metabolized.

 

[Wrasse-cal]

I agree with both of these statements, although, as you point out, the acetate doesn't "count" in terms of alkalinity until after it gets metabolized.

How quickly does this metabolism occur?

 

[Dan_P]

How quickly does this metabolism occur?

Probably within 24 hours

 

[Ferrell]

I started dosing kalk in the beginning and as soon as it would keep up with evap I just supplemented with two part.