The water changes basically consist of taking the water directly from the filter output of the under stocked pond where the tank sits in. Parametric wise, the water in both the eel tank and the pond should be of the same values. It's not water coming from the tap with different parameters, and needing to be dechlorinated.Why daily water changes, do you not have a filter?
Water changes are disruptive to a new fish. Once per week or less should be enough.
I believe this is alright? But do correct me if I'm wrong.