I have searched for hours trying to find a answer for what seems a simple question lol, I bought my 1st set when I was 10 and never had much luck but 12 years on I got one for fun and it has turned out great having 40 of the critters swimming around

and. I have now invested in a little 3 litre tank to give them a better home because I find them very interesting to watch, I have filled the tank with distilled water and have a aerator and heater ect but just want to know how much salt to add, i have natural evaporated sea salt which are quite coarse grains , please any one just a rough idea of how much to add in English eg tea spoons lol help would be much appreciated because I'm very much in the dark and don't want to wipe them all out