I have just purchase a RO/DI system and would like to start making salt water. How difficult is it to make salt water in small batches? I do not have a huge tank and would like to make salt water in 5 gal batches. I hear some people talking about putting water in a garbage can with a heater & power head. I really don't want to store that much water. What would be a good salt to purchase? Can I just mix the salt with RO/DI water and then add to the tank or do I have to "age" the water or run tests on it? Thanks.