I agree get a refractometer. They are more reliable. If you want to increase salinity just add Sw instead of FW till you get where you want it to be. Where is it now and where do you want to get it to. There is no "best" saltmix out there. They basically have their weak points and strong points. Just get what`s basically available to you and try that out. If you do a search on the site here you can see what folks use and why.