Howdy there,

Locked Power Spheres values can still be increased when you gain additional mana income.

Let's say you have 100 power, assign 20 to your Mana Pool and lock the sphere. If you get a shrine, temple, or your population increases (for races that pop generate mana), there is a chance that the increase income will be added to that sphere.

I'd assume that if I lock a sphere, if new mana comes in it would be distributed among the unlocked spheres. (With the exception being that all spheres are locked. )