thank u both for your replies, i searched on google for some answers and it said i can take them out completely and i can put filter wool in its place so im gonna do that then replace one side everytime i clean it. i also read the sponges only really need to be changed wen they are nearly falling apart.
hdultra your really only saying what the box says but i know that companys that make these items say to change them that often to get more money from you and i have seen a thread on this site talking about a different filter saying u dont need to change the sponges as much as they say thats why i thought id ask if anyone had one and what they do.
warthog76za i agree i havent changed them like they say but i thought it was a good idea to find out if i can remove them as they r only really needed for removing meds n that. and other people have said to replace them with filter wool so ive brought a 5m roll off ebay so i can cut it to size and ill have plenty to last me a while. the best thing it only cost me £6.50
anyway thank u both again for your replies.