"Dump the chips in the old filter"
u mean dump them(the chips) out to the garbage right? i dont need these chips anymore.. the old filter will keep running with the drity filter floss only(no chips or anyhing else, just the floss.), i wont remove the old filter even after 2 weeks.. so ill just have 2 filters. tommorow evening when i will install the new filter, before i take out the old filter out so that i can dump the chips i will FIRST do the 25% water change so that i can finish my treatment proccess. then like i said ill take out the old filter, dump the chips to the garbage, so there will be only the dirty filter floss left in there. ill put the old filter back in and then ill continue with instaling the new filter, like i said i will run it WITH carbon for a week and then i will remove the carbon. after 2 weeks of running both filters together, i will check out the filter floss in the OLD filter and if its too dirty ill just take out the old filter and completely dump the old filter floss and il simply put a brand new fresh filter floss in the old filter. regarding the sponge in the new filter, i will just rinse it every month or so with aquarium water.
All good? that was a summary btw. i wrote that to be sure i understood all correct.