Topping off pond

Hi all - I didnt really think twice about this is the summer, but should I
be concerned about the temp of the hose water being quite different from the
pond. The hose water is about 68 and currently the pond is 52, but
obviously it will get lower.

Also my pond is only about two feet when full. Is this too shallow for the
bottom water to be warmer, ie - will topping off affect the temp in the long
run.
Thanxx
Bill Brister - Austin, Texas