A quick look at my goldfish tank I have changed the standard Aquaone light as it is way to bright for a low tech goldy tank and replaced them with a freshwater maxspect R420r nano and built some new lids out of twin wall Polycarbonate
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https://www.youtube.com/watch?v=DoNRym-RDj0
ALL IN ONE SYSTEM - 11W UV STERILISER / 2500L/H PUMP / FOUNTAIN. Got this instead of using a standard out of pond flow through UV
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https://www.youtube.com/watch?v=WIiQN-0sBwk