I have huge amounts of bullfrogs and other kinds and have never put any frogs or tadpoles in the pond. What I noticed is when my pond was new I didn't have frogs. Then when I had the heavy infestation of Eurasian Milfoil they just showed up and loved to sit on top of the milfoil that was on top of the water. When the GC denuded my pond of vegetation the frogs mostly disappeared and came back when I reintroduced vegetation. They go where the food is and vegetation has lots of bugs. My dog Dolly catches several a day just to play with. The turtles and frogs coexist well together.
One of the best things about frogs is the tadpoles eat algae.
