It seems excessive to use sea salt every week. Once every 3-4 weeks would be good.
Judging from the shape of the leaves, it seems that the problem is not caused by a disease.
The occurrence of certain pests frequently causes the leaves to curl.
If pests are a problem, try adding 1 kg of NaOH.  

I have contacted my local authorities they said its mosaic virus and cannot be treated. Should we use 1kg of naoh for making 500liters of pesticides?