kalk question

[Greg Grasson]

Why do some people adding kalk also add alkalinity boosters? Won't Kalk alone sufficiently buffer PH, boost alkalininty, and provide calcium?

[dragon_slayer]

IME kalk is a very closely ballanced buffer which provides both Ca and Alk, and it's also been my exp that most often you'll need to add extra Ca rather then an Alk buffer, but over time kalk will almost always need a boost one way or the other.

hth
kc

[Randy Holmes-Farley]

I agree there are various things that very slowly tip the balance one way or the other, the most common of which are water changes that do not directly match the tank water. Another is that the nitrogen cycle, when run to the point of producing nitrate and not any further, depletes alkalinity slowly.

However, many folks also misinterpret what is happening in their aquaria if the limewater (kalkwasser) is not quite keeping up with demand. In that case, the levels of both drop, and calcium drops by only 20 ppm for each 1 meq/L (2.8 dKH) of alkalinity. Folks experiencing small drops of each sometimes see the alkalinity part easily, but miss the calcium part due to uncertainty in their calcium test kits. So they think they need alkalinity, when in reality they need both.