Reefoctopus that I have had for many years. Works good no issue until I went to unscrew the grey fitting to disconnect the pump so I could clean it and it won't budge. It doesn't look cross threaded but it may be. I have unscrewed this 1000s of times without issue. I tried Chanel locks and it won't move. I don't want to break anything. Any bright ideas on how to separate the pump from the skimmer. I'll attach pic.