I wet vaccum all water out through the controller. Then I pump RO water 0-7ppm into the system, dump in FNB about midway, through some PH up in as well. Somehow 100-120 gallons I just freestyle dump and am always just about deadon. I let it cycle for a couple hours, and make final adjustments. Next day after 24 hours of stabilization I check and adjust if needed, usually I don't. My auto topoff is PH adjusted to 6.0, I like to start around there and drift down. I know I should mix nutrients in a seperate tub but I have never had any problems.