hi everyone someone has just given me an air driven sponge filter it is quite big, i have never used theese before im wondering what peoples opinion were on them, im thinking of adding it to my 3ft goldfish tank which already has 2 internals but with goldfish you can never have to much filtration!! what do you think. there is already an air pump for that tank so it would just be a question of using that instead of an airstone.thanks

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