Planted Tank Enthusiast
Join Date: Dec 2011
Location: Rockport, Texas
Water softeners replace each Ca and Mg ion with two Na ions, so your softened water has a considerably higher TDS. Plus, you are adding Ca and Mg back into your water with Seachem Equilibrium, which raises the TDS even higher. Your softened water could easily be too salty for many aquarium plants.
The general consensus is to not use softened water for planted tanks.