Water depth balance in multilevel small pond

[Deanery]

I have constructed out of preformed ponds with spill ways a small 75 gallon, 3 level pond. Water is pumped with a 290 gph pump from bottom to top. Tubing is 3/4 inch, rise about 1.5 feet, spill ways about 6 inches wide. My problem is that over a 12 hour period the water in the lower pond drops by about half and the water in the upper levels increases. How do I maintain balanced levels? The water returning through the spill ways is clearly not sufficient to keep the lowest level full. Do I need a bigger pump or do I need to use a valve to slow the water going to the top level? Any suggestions would be greatly appreciated.

 

[j.w]

@Deanery
Not sure how to fix your issue, sorry.