>A few people in SA keep a small amount of limestone in their
aquariums to provide calcium (I presume) in the tank water. I suppose this
comes from the idea that most of the water ways (eg. River Murray) are cut
through limestone. As there is this constant contact with limestone wouldnt
this mean that calcium levels, through dissolved limestone, be permanently
at saturation point?
One of the important factors in this case is the rate at which the Ca++ would
dissolve in the water. Factors that control this are temperature and pH,
allong with the starting concentration of Ca++ and other ions in the water.
It takes a long time to reach the saturation of Ca++ from calcium carbonate.
So, from this
discourse - no the Ca++ is not a saturation. The river system the fish are
from may or may not be at saturation also. One of the jobs I had as an
undergraduate was performing assays of river and stream water and I spend
hours and hours with the grad students trying to understand their data.
Scott Buckel (RSG)