More than 10 passes doesn't make sesne, think that you are squaring the values, so (((((((((((3^2)^2)^2)^2)^2)^2)^2)^2)^2)^2). (I may be wrong, but it was doing something similar to this as far as I can remember)
It's more or less that you are aiming to "3,7339184874102004353295975418487e+488" passes... a bit impossible IMHO hehehe
So the thing is to find the balance between initial passes and total passes :)
And about buckets not being square... why is that so important to you?
Cheers.