Anti freeze into fresh water tank

I have done it that way, but like someone pointed out it takes more antifreeze. I have a Wayne 12 volt pump that hooks to the battery.I use it to put water in the tank if we have no campground water connection.But it also works great for putting antifreeze in. I stick the pick up end in the bottle and the other end attaches to the fresh water connection.Of course I drain everything and blow out lines first.It takes about 1.5 gallons of antifreeze to purge the lines. Then I use another 1.5 gallons in the traps and the holding tanks.