Originally Posted by Gregcoyote
Kalkwasser is the cheapest and most efficient way to go. You can maintain calcium levels with two part solutions and purple up, but it takes Kalkwasser to raise them to the right levels. Also a good salt mix will help as some of them have high calcium levels when mixed. Kalkwasser is cheap.
I also somewhat disagree. You definitely can't maintain calcium using Purple up, unless your demand is next to nothing, plus Purple up does nothing for alk
. It's best to use 2-part calcium and alk
dosing to get your levels where you want them, especially since you may need to adjust one more than the other. Then use kalk
to maintain those levels, if your demand is low enough where the kalk
will keep up.
What Your Grandmother Never Told You About Lime by Randy Holmes-Farley - Reefkeeping.com
"Limewater that is saturated with calcium hydroxide has a pH of 12.54 at 25ºC. It is actually recognized as a secondary pH standard. ...Saturated limewater has a conductivity of about 10.3 mS/cm at 25ºC, and contains about 808 ppm
of calcium and 40.8 meq/l of alkalinity."
"The fact that limewater is very basic (the pH is typically above 12) demands that the limewater be added slowly to an aquarium unless very small additions are made. The reason for this is two-fold: to prevent the local pH in the area of the addition from rising too high (slow addition permits more rapid mixing with tank water to reduce the pH), and to prevent the overall tank pH from rising too high (slow addition allows the tank to pull in CO2
from the atmosphere during the slow addition, mitigating the pH rise). Some aquarists advocate rapid addition
, and that is fine for small additions that would add less than 0.2 meq/L of alkalinity to the aquarium, but larger additions will drive the pH too high..."
"Another important consideration for limewater is the upper limit of the amount that can be added to an aquarium. This limitation exists simply because both the amount of water that can be added to an aquarium each day (to replace evaporation), and the amount of solid lime that can be dissolved in that water, are finite."
"If an aquarium’s calcium and alkalinity demands are near the high end, then replacing all of the evaporated water with saturated limewater may not be adequate. ... Additionally, aquarists often use a small amount of one of the other balanced additive systems (especially the two-part additive systems) to give a little boost to aquaria that need a small amount of extra calcium and alkalinity beyond what limewater can supply, without incurring significant capital costs. Likewise, these two-part additive systems can be successfully combined with limewater during periods of low evaporation when limewater may be temporarily limited and not meet demand (as during rainy cool weather).."