Love the tank too. Very unusual and cool looking.
When you say rock salt, is it the same as table salt sodium chloride?
100 US gal = 378.5 kg = 378,500 g
30 tbspn =~ 150 g ... depends on how fine the particles are, their shape, how packed the powder is, etc., so could be more...
(150 / 378,500) x 1 million = 400 ppm of added salinity (this is in addition to your natural salinity in your source water)
Low end of brackish seems to begin at 1000 ppm so this is indeed unlikely to be brackish.
The historical data seem conflicting, with older school saying that there is usually nothing wrong with having a bit of salt in water all the time while there are some health benefits.
New school says yes, there are short term benefits but this leads to a long term stress build up and will eventually result in illnesses and premature deaths.
Like you yourself speculate on the possible difference between the silver dats harvested from freshwater and from brackish water and their long-term potential in our freshwater tanks.
I understand you are aiming to walk a thin invisible line... Interested to see what you find. Do you have a thread where you'd report your observations over time all in one place?
