Generally speaking, I recommend no salt at all (0g/L) when all is well.
If fish are stressed, or you’re treating fish with disease, then up to 2g/L if planted (plants do not tolerate high salt), or up to 5g/L in unplanted ponds.
Times of stress include fluctuating temperatures (as occurs in spring and autumn), or very cold temperatures (<10 degrees Celsius).
At times of disease, you’d use this in conjunction with most other treatments.
NB: g/L is equivalent to ppt (parts per thousand).
