So it turns out I was missing a rather critical part of the Oase BioPlus thermo 50 filter, thanks to @FishShopMatt for pointing this out when he watched the original video:
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I reinstall this filter and check for how much gunk it has pulled out in less than a week during this video. A few shrimp were found in the filter but this happens with almost every one, the fish are happy and healthy this time!
I’ve got to say Oase were brilliant and so fast with their customer service.
