WATER PUMP OUTPUT REQUIRED TO ROTATE 22 LB. BALL

I purchased a second hand 22 lb. floating water fountain granite or marble ball along with a ring for it to set in and a SKYISH submersible fountain pump Model TP-500.  The aluminum ring is coated with a finish.  I have no idea if the pump originally came with the ball or if it was bought aftermarket.  The ball floats on the jet of water but it does not randomly rotate.  The ring shows wear in multiple places around it.  I suspect one cause of the absense of rotation is due to the jet of water escaping thru the wear along the ring.  Is the number 500 on the pump some indicator of aN output rating for it?  Should I look for a pump with a rating a little higher then 500 or should I stick with 500 and and repair the wear on the ring?  I tried increasing the pressure of the pump jet by narrowing the nozzel by inserting a smaller jet into the larger nozzel but I saw no rotation take place so I removed it.  Could I achive rotation if I were to polish the ball and what would I use if this would work?  Any one know of any north america distributors and retailors of floating stone ball fountains that I can contact so I can ask them for info on the water pump output requirements to get a 22 lb stone ball randomly rotating?