Calcium deposits on leaves
I have had a decent amount of calcium deposits on the leaves of several species of plants, mostly on older leaves of plants such as cryptocoryne, large valisneria and dwarf sag. I have the least on my limnophila. I have a 40 gallon with 4x 32 watt T8 bulbs, I don't have CO2, (they are wider then the tank though) and it is uncovered.
I haven't seen much calcium in my lower light 10 gallon tank.
The water around here is pretty hard. I was pretty lazy with water changes for a while, but I have a few hunches. Is the excessive evaporation causing the water to be too hard, or are the plants using CaCO2 for carbon, leaving calcium to deposit? maybe both?