I tried this years ago and it didn't work in any reasonable time. I even tried much higher voltage (150 volts).
I'm too old to wait 18 hours for an unknown strength of colloidal gold. I don't even buy green bananas.
Whats wrong with making it with food? That's what we do with the electrolysis process.
I can make a quart in 7 minutes, and know the ppm exactly using gold chloride, maltodextrin and sodium carbonate. The chloride is removed, maltodextrin is food, and sodium carbonate is a common food additive which I'm sure you have consumed many times. This is the fastest and most accurate method.
Show us the pictures.
Just remember like Colloidal Silver the full color normally takes a day until the solution reached its final color.
Not if you make it right.