The pump should lift straight off the top of the box. The white floss at the top of the filter is the only thing you need to be changing regularly, the other sponges should only need to be changed every 3-6 months and then only one at a time. If the sponges are getting clogged just take them out and swish around in a bucket of water from the tank, that way you won't lose any beneficial bacteria or cause the tank to cycle.