Questions on Kalk, what it is its use and using with vinegar

James w Lewis · Oct 9, 2015

1 What exactly is it? 2 when you mix it with water and then pore the water off what is left and why cant you use this again? 3 I read that you can dissolve the kalk in vinegar till the kalk stops dissolving and then put this concentrate in the tank or mix with top off water, correct or no and what is the process to do this correctly. I just bought a ATO unit to add kalk to the sump in small amounts. Just making sure I get this right.

kv69 · Oct 9, 2015

Search kalk use and Randy's article will b close to the top. It will entail all you need to know. Vinegar is a form of carbon dosing. Randy also has an article on this as well. Its all here in the forums you just have to do a little digging.

I'm sure one of the guys on here has the links readily available.

Randy Holmes-Farley · Oct 10, 2015

FWIW, I dose limewater (kalkwasser) with an ATO and vinegar with a dosing pump. I choose not to combine them to allow better control over the time and amount of vinegar dosed (independent of evaporation).

If you mix vinegar into limewater, that allows you to dissolve a bit of extra calcium hydroxide. Adding 45 mL of 5% acidity vinegar into limewater will allow about 3 level teaspoons of calcium hydroxide to dissolve instead of just two per gallon of RO/DI water. So it is a way to dose extra potent limewater, and also delivers vinegar to the aquarium (for organic carbon dosing, whether that is intended or not).

When mixed, the solution contains calcium ion, hydroxide ion, and acetate ion.

I do not know what you mean by "can't dose it again".

Alternatively, if the goal is primarily dosing of the vinegar and you just want to offset the pH lowering of the vinegar, you can dissolve calcium hydroxide directly into vinegar until there is excess solid calcium hydroxide, and you can dose the clear liquid with no concern about pH lowering. It is a stable solution. However, I would not dilute that without adding a lot more calcium hydroxide because the pH may become low enough for bacteria to grow in it, ruining it.