I have used one for the past year. I love it. A couple of observations however.
1. Disconnect the venturi pipe, with it, it sounds like a gargling granny. Without it, its near silent.
2. Make sure you mount it tight against the glass. Got a bit sloppy once, didn't push the unit up close n personal and ended up with a few tetras getting wedged. Soon learnt where to look for missing fish.
Bang for bucks/pounds I think that this is a fantastic unit. Just make sure you keep a spare heater available if it ever breaks.. Obviously if the filter breaks you are going to have to buy another one or separate units again...
As always--- my opinion only
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