Uhhhh plants don't battle algae Jocelyn.-Mak- has the correct explanation, it’s a “carbon substitute” similar to sugar and sweet and low... both sweeteners, but chemically very different. Also note, it’s a “carbon substitute” not a “carbon dioxide substitute”
Current thinking on carbon substitutes is that they work more as an algaecide then give carbon to plants... this gives plants a leg up against having to battle algae on their own, in effect letting their energy focus on growing vs fighting algae as well.
Ahhh okay I get you.They do, in a way, sorta ... one of those things hard to type.
A weakened plant becomes prone to algae growth... the algae once on contributes to further weakness (can’t figure out a better way to type this)... by eliminating the algae through excel, the plant can ‘direct’ its strength towards healthy growth..., algae isn’t using nutrients plants need, blocking light, etc etc etc... excel is basically the ‘high tech’ version of removing older weak leaves... hoping this makes sense.
Certainly not advocating for excel, personally don’t use it, find it better to balance a tank semI naturally... however, for others it can be an aid in their battle/balance...
excel helps to tip the scales in the plants direction (ever so slightly)