I would use the original pump as a backup and for chores like water changes or running a UV light, waterfall, fountain or accessories. If you have had the pump for a while you should make sure it still works. Too large is better than just enough. It would take a lot to make too much water movement.

Thanks for your input. Yikes! UV lighing. My budget won't allow that at this time. I will look into another pump and use the original as a backup.

Look into a mag drive pump like Pondmaster, they use less electricity and can't leak oil.

Thanx for the info on the mag drive buyorsell888. I'll look into that as well.

your pond is 4500 gal.i would go with a external pump,and you could add a waterfall filter.one of the best pumps is a preformance pro. the 1/4 hp pumps 4900 gal/hr, 9 1/2 ft high with out loosing any pressure.it uses about 300 watts.

joe_09,
A bit more than I can afford at this point. But thanks for the information.