The power head should turn off in the event that one of them fine their way up there. Had my water tested at the local fish store and fond tds's at 40. I'm now getting my water from the fish store knowing their water is at 5 tds's doing a ten gal water change tomorrow with different water then water and ice.Get a Triton test done. I had black sand that was leaching Aluminum and that caused all sorts of stress. (mostly corals closed up long-term)
And do you not have powerhead covers and an anemone in the same tank? (that spells fail)
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