"IKD" writes:
I put two Water Lilys in my pond last week. The tadpoles seem to love one
plant in particular and have just about stipped the pads .

Could you surround the lily plant with an underwater bowl-shaped barrier
fashioned from nylon flyscreen and fishing line? All that would be visible
above the surface would be a circle where its edge emerged above water
level. Terminate it on a circle of floating plastic tube, cover with weed.
In time the fly screen would become mossy, and you'd need to check from
time to time that no frog spawn has hatched inside the barrier.

This idea stands a chance of working if it's only the pad that they are
eating, and not the stalks too.
--
John Savage (for email, replace "ks" with "k" and delete "n")