I agree... you need a good skimmer for a high bioload. I use an AquaC Remora on my 20g... and it constantly pulls out nasty gunk. I always skim on the wettest setting too for maximum skimmate.
This is totally off subject but how do you have a mandarin in your 20g? Does it eat prepared foods?
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20g BB Mixed Reef // Coralife 150w HQI // AquaC Nano // Koralia 1 & Seio 820 // Jager 200w // AC50
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