The higher the water level the more psi is placed on the pond bottom. So, the jury is still out. But, from what I'm seeing, I think you'll be O.K.
Now are you still thinking that the overflow pipe is too small??
The water that you are seeing now is why you heard from a few different people that a bigger overflow pipe is better than a smaller one.
I'd wait 'till Spring for an alum treatment. You want to have the banks covered with plants to prevent more clay from washing into the pond before the treatment.
