Thank you for contacting us. Once you put the skimmer in water, it will not be an issue. The skimmer is not balanced when it is dry BUT it was not meant to be dry. The skimmer is meant to run in the water where the balance is not a problem.
You should always install the pump last. After you have place the skimmer in the water with the correct water depth, then you can attach the pump. If you attach the pump before putting it in the water, you will be putting a lot of stress on the joints and may cause damage to the skimmer. Such damage is not covered by the warranty.
So, install the skimmer where you want, let it fill with water and then attach the pump. That should give you no issues and will work correctly.
Regards,