My TDS tester
Sorry but being part blind doesn't help. I have a Health Metric TDS tester with PPM and EC . My master blend when tested comes to 659 on ppm and 1381 on EC I don't know which to use as my bok choi was doing great and now I have brown edges on some leaves . Is my mixture off as I feel and what is a good range for ppm for bok choi.