Each liter of seawater contains, on average, about 13 billionths of a gram of gold. (Source NOAA) http://oceanservice.noaa.gov/facts/gold.html
Assuming 100% extraction you need to have 1/13*10^-9 liters of fresh sea water pass by in very close to the electrodes. That's 77000 cubic meters for one gram.
The price of $99 for a basic unit is claimed to repay itself in 45 days. Which is about three grams of gold. That's 230 thousand cubic meter per 45 days or close to 5 thousand cubic meter per day... or 60 liters per second.
Is it possible to extract such a diluted source that fast to 100%? If not then the flow rate must go up. Is it even plausible that you have that flow around a buoy just off shore?
Remember that to recover a gold atom it has to be close to the electrode, like less than millimeters off it or it will just flow past.
Justin, what do you think?
Göran