Just put inside the assigned slot and turn. This is a huge improvement in my opinion. The device also has an inside TDS reader which displays over the front in the unit. The best part on the device is the little number of space it will take up. It really http://paxtontvdix.blogacep.com/14383844/how-how-much-does-a-gallon-of-water-weigh-in-grams-can-save-you-time-stress-and-money