jacblades
im not the jedi i should be
smallworld makes filters for bowls. i dont know if you have them in th uk though they make ones that look like the penn plax filt-a-carb and ones that stick staight up in the middle of the bowl and have filter attachments like some undergravel filters. those kinds of filters require air stones and therefore require valves on them so the turbulence wont be too strong.