Moving the powerhead might be a temporary solution? If you are using a sump or reactor; have some extra carbon ready in case the sea cucumber decides to wander into the powerhead or decides to self implode
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I have a tank of anemones and its inevitable that some unfortunate event will happen....no matter how well you plan. So.....I try and have an 'emergency' kit ready for such occasions (which includes high grade carbon and extra reactors).