OK, having to be budget conscious these days, I bought one of these and it works ok. Its pulling some greenish skimmate in 24 hours and producing a swirling pattern of 0.5-1mm sized bubbles. I'm using a 800L/h pump with it.
It comes with a 'bubble eliminator' for the outflow which consist of a big tube and sponge about 3 or a bit more inches long and about 3 inches wide, yellow sponge, unsightly in my 25g tank (since its hang on back, no sump yet). I removed the 'bubble eliminator' and have now got the flow going direct into the tank. There are small bubbles coming from it and some current, but it sure looks better without the sponge.

Question: Is it ok to leave it like this?

Thanks.