Question 1025591
This is a very complicated question which is even more complex than your previous question. 
First step is to determine the first level arrangement which is difficult.
The next step is to determine the second level arrangement based on the first level arrangement which is even more difficult. 
The remaining levels can be copies of the first and second level so that step is more straightforward. 
You also need to keep track of the volume of spheres, the original volume of water in the tank, and the updated volume of (spheres and water) to know when to stop adding spheres.
The top level of spheres will either be a copy of the first level or the second level so that step is straightforward once you've determine the level arrangements.
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Is this is research topic, homework problem, or an experiment you're setting up?
Also what level of school is this?
Are you looking for closed form solution or approximation?
This would require computer simulation to determine a solution, I believe.
Based on your responses, we could determine what the next step could be.