A laser pointer will display the Tyndall effect, achieveable only by a true colloid.
You can estimate the ppm by measuring the resistance between the electrodes at the start of the process (about 2ppm) and multiplying the ratio of the resistances by that 2 ppm.
start resistance: 50K ohms
desired ppm: 50 ppm
50 ppm / 2 ppm = 25
50K ohms / 25 = 2K ohms
So 2K Ohms is your target resistance.
That means you keep the process going until you reach about 2K ohms between the electrodes.
You will notice that the colloid is completely clear when you reach the desired ppm.
You may be worried that nothing has happened.
This is a time to demonstrate the Tyndall effect.
1. Shoot a laser pointer through the distilled water you start with (no bubbles)
2. Notice that the laser is not visible as it passes through the clear water
3. Make your SIlver Colloid with the MicroGen
4. Shoot the laser through the clear liquid again. THE BEAM IS VISIBLE.
This is the Tyndall Effect and assures you that the colloid has been made.