max head height

Question
hi there
I'm an artist preparing my degree show in June,
I'm making a sculpture with 65 liters of water in the plastic bin approximately 60 cm high, 4kg heavy 40 cm diameter hollow stainless steel sphere floating on the water and a water pump placed in a bin on the bottom.
the idea is to introduce a movement into water so that the 4 kg ball will rotate on the surface of water.
I need an advice which pump or rather how big the max performance and the max head should be.
I hope you could help me with this or point me to the right direction.
thank you very much  

Answer
Hey Hye, you sculpture sounds very interesting I would like to see it. I wouldn't think you would need a very big pump. But since this is a new idea with the water is going a certain way if I were you I would get a medium sized pump and put a valve on it so you can let out as much or as little water as you want because you are the only one who will know when its right and you can experiment with your water flow and get it just the way you  want. Thanks Eric