To reuse the waste tank is simple but a little messy. The plastic grid over the top simply snaps off and then the saturated sponges can be thrown away. The sponges are friction fit and will slide out once you get hold of an edge. I used to use sponges from the hardware store that were similar to the original. I hate to say what I use now but it's available at any drug store, comes in large packages, no man wants to be caught buying them, and has a handy adhesive strip to attach to the lining of the tank. I just stick one to each side and the bottom.
Here's the reset procedure that I used to use for the 4000 (middle of the page)
http://www.northlight-images.co.uk/article...nance_tank.htmlI don't know if the 7600/9600 procedure will work with the 7800 but it's probably worth a try.
With the xx80 versions of the epson printers you have to get a chip resetter which is cheaper than buying even a single waste tank from epson. I got mine on ebay from a guy in Montreal (ebay ID=computerknow) and it works fine.
Epson is one of the LEAST green companies on earth, sorry to say, and they actively prevent owners from re-using anything by changing firmware, lawsuits against cartridge refillers, refusing to recycle etc. Shame on them.
Good luck
Doug