Originally Posted by mattcham
I think Dav3 primes once to remove bubbles, but NEVER need to prime again even after power failure. From my understanding there should be no bubbles even in the event of power failure assuming you properly sealed the airline nipple socket. Is this correct?
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CPR overflow box has a different configuration than what Dav3 has. CPR has a surface skimmer which creates bubbles every now and then. Some bubbles can also come from other sources like your power head installed for surface agitation. When power comes back after brown own your return nozzle will also create bubbles when it is above surface. Some HOB
skimmer will produce micro bubbles specially just right after a pwc
. Any bubble floating that passes though the CPR overflow will get stuck and collected at the top of inverted U shaped chamber since air is lighter.