Ok just did GH, and the reading was 100mg/L or about 5.6dH (i think) which im guessing comes in The slightly Hard category, so maybe its not calcium causing the problem.
Ok So my fert and tank maintenance routine. I do 50% water change weekly. To the tank i add 5-10ppm nitrates per week, which then makes pottassium added ~3-6ppm per week, about 0.15ppm Iron (edta chelated) per week and then micros. My Phosphates usually stays at about 0.1ppm, pH at the moment is 6.6-6.8, KH is 60 ppm which makes co2 levels around 18-25ppm.
Tank is 10gal, with swords, polysperma, ambulia, glosso, wisteria and another unknwn plant. Only sword and polysperma show curling (sword has root tabs under it as well).
Ok anything else ya need??? i havent dosed potassium on its own for weeks and weeks, only with the nitrates