Using an automatic top off (ATO) system for replenishing freshwater in your saltwater aquarium is the easiest way to replenish water lost to evaporation. Topping off is important because as water evaporates, the salt and other elements in the seawater stays behind. If your tank is not replenished using purified freshwater on a daily basis, your tank's water level will drop, your salinity will rise and the general water chemistry will suffer.


Ryan saves you the hassle of learning the lessons the hard way and gives you the best ATO option alongside valuable advice for keeping your tank chemistry stable.


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Tunze Osmolator ATO