I'm already using this calculator, but doesn't seem to be correct. Check the attachment.Some Cl sensitive species suffer when Cl is above 20 mg/l, therefore Cl shouldn't be above 20 ppm. At the same time, plants do need Cl. Use CaSO4 and CaCl2 in combination. For example, 8 mg/l Mg with 32 mg/l Ca ( 28 mg/l from CaSO4 + 4 mg/l from CaCl2 ) is a good concentration resulting in 7 mg/l Cl.
Use this site for calculations : https://rotalabutterfly.com/nutrient-calculator.php
First let me mention this, although you might already know
Chlorine - Cl, chemical element
Chlorine gas- Cl2 --- toxic, keeps water clean from bacteria
Chloride -Cl-, anion of Cl, like in sodium chloride ( table salt)
CaCl2 is not considered toxic or an water disinfectant. I used to use CaCl2*2H2O for my remineralization but did not see any major change in plant growth. The ion is transportable in plants and in terrestrial plants it can cause problems in saline conditions , however aquatic plants don't 'pump' water from the roots to the leaves where it evaporates so this alone changes the dynamics of accumulation. Far as I know, fish also won't be impacted from 5GH coming from CaCl2*2H2O