Acclimating marine fish .. procedure.

i understand acclimating fish over a 2.5 - 3hr period to your tanks parameters, but over that time your removing at least 2 litres or more from your display tank right during drip acclimation, so naturally ill have my ATO, off during this period, but then once i add the fish is it a good idea to have some fresh rodi saltwater prepared to add back to the tank to bring it back to the right level then turn my ATO back on so it doesnt throw my salinity out of whack by dumping fresh rodi into my saltwater when its not at the right level .. just curious thats all .. i know its a bit unusual .. just thinking out loud and want to make sure i do it right to keep my parameters in check.

thanks for anyone that can clear this up for me.