"Different strokes for different folks" I like to mix my own and have control of my water..
Is up to you! if you don't care about hauling a bunch of water every week or bi-weekly then buy it mixed. You might wanna check salinity cause most of the time this pre-mixed waters have a lower salinity than 1.024-1.026...which i don't like..
I originally thought my guy made his own salt water but then he told me that the water is PULLED right out of "DEEP OCEAN" I didnt get into details on how but will next time.