Need help with microbubbles !

[Delphinus]

Baffles are the best way to go.

Adding additional bends in the lines, I don't think will really help. This will only increase the backpressure on the lines meaning the water level will be higher in the main tank.

You could also maybe look at using a larger bucket, perhaps a 5g (it would have to sit outside the sump so some creativity is in order), but, I think the baffles will work better.

As far the Durso flushes, it does sound as if there is some kind of air adjustment still needed. Perhaps the current holes don't allow for enough intake? Can you take some pictures with close-ups of the dursos and your overflows?