Christopher,
Thank you for contacting us. It sounds like something got stuck on the impeller or something got stuck on the skimmer's output that was blocking or reducing the water outflow.
There are two main reasons why a skimmer would overflow:
- Something is obstructing the outflow so the skimmer is intaking more water than it can push out
- You have added some type of chemical to the water such as stress coat or water conditioner where the skimmer creates excess bubbles and the collection cup overflows.