im growing in coco from seed.. 46 days since 12/12

went away on holidays and came back to this.. the plant in the pictures is the worst but the rest are slowly showing signs on the leaves.. a week ago i thought they were showing signs of a calcium deff so i gave them 10ml of calcuim per 5L on two consecutive waterings..

im using the usual canna nutes ec of 1.5 to 1.8.. i have not been feed feed watering i was juat feeding nutes with some run off for the past 2 weeks... last watering i used water with florakleen with alot of run off..

did i do the correct thing or what i am doing wrong and what can fix my problem asap.. i dont want to lose much yeild..

thanks in advanced..