Well, you can...but you don't need to. The generators "Auto Off' works just like a meter. It shuts things down at a very exact point. After that point [with the series 2 generators only] you can bypass the off and continue on in an accurate fashion by timing the batch. The 'auto off' gives you an accurate start point for timing.

Timing alone from the start will not work due to the accelerating "Ramp up" of current to the controlled setting and because you don't know where you started so far as PPM is concerned. After the generator shuts off, you know where you are 'as if' you had used a meter to determine that.

Once the current controls kick in, PPM production is strictly linear and predictable because ion production is a function of current and electrode surface area. The electrode surface area changes little [as long as it's still all there], the current...not at all.

Note that heavy deposits on the electrodes can 'fool' the circuitry and prevent timely shut down. Wipe them off if they form.