esshup, I wasn't familiar with TDS units so I googled and found that it is usually expressed in mg/l (parts per million). Salinity is more often expressed in parts per 1000 (g/l) but it is easy enough to multiply by a thousand to convert to TDS, mg/l, or parts per million. I google the TDS of seawater and it is 35000 parts per million (mg/l)

It isn't what we don't know that gives us trouble, it's what we know that ain't so - Will Rogers