Bubbles?

[bigrf33]

i have just got a v2 nano skimmer, if i put it in middle chamber do u just use it instead ov sponge in ther? have it in 3rd chamber at min and bubbles in tank, how do u stop this heard sponge in outlet helps? which outlet? i have a d&d 24g nano tank. also how many fish will this allow me 2 keep? hoping 4 to 5 small fish. thanks.