Bubble MagusQQ3 Hang On Nano Protein Skimmer External Sump Pump Saltwater Marine Reef Needle Wheel Venturi Pump for 300L Aquarium Tank

Once you accept that the “instructions” are almost worse than useless, the skimmer itself is excellent! I used the trick mentioned by one of the other reviewers to adjust the bubble density - a small length of airline attached to the air intake with a regulator valve to reduce air flow. Even so, I took a while to get the skimmer started. then I realised that by sucking air out of the air intake - in my case, by attaching a large syringe to the tubing I used to regulate airflow - you can get the skimmer primed and flowing in a matter of seconds. Persevere with it - it really is worth working around the truly awful instructions.

Poorly constructed, constant leaks. Requires DIY fixes to get half-working

Extremely quiet skimmer. So far I'm very impressed and it has bedded in very quickly.The instructions weren't great but having had a skimmer before I knew how things should work.Initially I found that the cup consistently filled up straight away with tank water not matter what I did. So I eventually attached a small amount of tubing to the silencer(air inlet) with a "tap" on the end ( from my old skimmer) so I could regulate the flow of air and in turn regulate the bubbles coming up the central tube. This worked and now it's bedded in I probably don't need it, but I'll leave it on. Excellent skimmer, would recommend.

This is the third skimmer ive tried and by far the best , comes complete with nothing to put together, fits perfectly on the back of the tank ,no need to fix it , works very quickly without any issues , tried the bubble magus e3 which would have been fine but the bit that screws to the tank is poorly made and breaks off ,tried an octopus which was too noisy ,this one is perfect