are you sure it said 10 day run,
i believe when i set mine up it said to discard the first 10 gallons
and yes is says to discard the first 10 gallons with the cartridge removed from the 3rd canister
ok got the instructions out , it says 10 days of continuos running is required for complete membrane hydration, during this time the water is still filtered and can be used as normal, although the output maybe low