3wk old marine tank

if you need to lower it, all you have to do is tanke some of the saltwater out, and put some fresh in. let it sit for a day to get good and mixed up. then check again, if its not low enough do it again. as long as there is nothing in the tank yet, it could get done in a day or 2. but if for some reason you have something in there already, you need to do it a bit slower. say its a 55 gallon tank, with nothing in it yet, just dump 4 gallons and replace with fresh, but if you already have some live fish or coral or inverts, only do a gallon or 2 at a time.