Agreed on the brand, but if youve never done it before i suggest read up on it as much as you can before doing so,...i us a 30 gallon trash can a heater and an extra power head i have put my RO water in the can turn on the heater and power head and slowly mix in the salt also using something to stir the water as well,..and once its all mixed leave in whatever container your using for atleast 24 hours before making the change...during that time is also a good time to add any trace elements you add for corals i.e. calcium iodide etc..if you have corals...and be sure to have testers for ph and salinity cause youll wanna match it as close as possible to your current water.....wow reading all this seems like alot...but after a few times either youll get the hang of it or youll say ta heck with it and continue buying premixed water..lol...