one thing that iv learned is that you always want to go with un-iodised salt(salt without iodine,iodine kills fish) instead of other chlorine neutralizing chemicals when you first start you tank.then all you have to do is addwater because the salt never evaporates only the water does.and if you r worried about amonia levels,local pet shops have amonia neutralizing chemicals and testers to test amonia levels.the one time i didnt use salt(i used aqua safe)all of my pacus died and so did my rainbow shark,luckily,my plecos and my oscars survived,but i turned my 70 gallon into a terrarium for my monitor.i plan on getting another big tank to start over and this time , im gonna do it right.also uniodised salt kills bacteria,diseases,and fungus harmful to fish.i wouldent recomend water changes cause it also uncycles your tank, which is also beneficial to yiour fishes health.