Ok, first of all I need to say that nothing below is new information. I gleaned everything from this site (well, mostly this site) over the last day of reading and following threads. This is just a summation for other new MX870 (or MX860 -- basically the same printer) owners to find with Google. A short background: Once upon a time I refilled carts. Back then (1/4 century ago) I had an HP500C and refilling was a nasty job of cutting cartridges apart. They could only be refilled a limited number of times before they had to be replaced. Then I got a Brother that had remote ink tanks with tubes to the separate printhead -- basically an OEM Continuous Ink Supply System that was easily refilled. I miss that thing. Naturally, when I got it's replacement, I leaned towards a CISS and my last printer was a Canon MP830 with a Rihac setup. It was fiddly and finicky, needed extra seals, had to be at exactly the right height to work and dumped ink all over everywhere when a line fitting blew out. But when it worked, it worked well and pumped litres of ink through the printer, saving me thousands in the process. Of course, Canon's chip ensured the warranty was voided by using a CISS, but every litre of 3rd party ink saved the cost of 3 printers. If I was to burn up a printer every year, I still saved money. That's not a warranty, it's a very expensive replacement program! So, despite the problems, when I bought it's replacement the other day - the titular MX870 -- I went looking for a CISS. Oddly enough, Google landed me at the German "Durchstich" refill method for the PGI-520/CLI-521 cartridges thread and I was surprised to see how simple, clean and easy refilling had become. As an added bonus, I can return to pigmented black ink for text (CIS systems don't really like pigmented inks). Some people seem to have trouble coming to grips with the underlying principle, but coming from a CISS background, this method of maintaining the internal pressure differential is so obvious I virtually slapped myself in the head and exclaimed "Now why didn't I think of that???" So I'm going back to the dark side, and here's what I learned (or think I learned) in the process: 1. The reason I was so confused about what cartridges fit the MX870 is because that all depends where in the world you live. If you are in North America, your printer needs cartridges prefixed with a "2" -- CLI-221 for dye based colour/black, PGI-220 for pigment based black. If you are in Europe, your carts are prefixed with a 5 -- CLI-521 and PGI-520. And finally Asians are looking for an 8, as in 821/820. Canon is apparently trying the DVD route to control pricing -- the chips are the only difference and a cartridge from one area won't work in a printer from another. An assault on the global greymarket economy. 2. The 221/521/821 inks are a slightly different tone than their CLI-5 predecessors. The ink itself will flow through the cart OK, but the colour will need to be remapped. The two most highly recommended ink types on this forum seem to be Hobbicolors and Image Specialties. Certain "mystery inks", usually from Asia, are suspected of causing damage to printheads, etc. Hobbicolors won't say were their ink comes from or who makes it, but IS is a US manufacturer of many housebrands and even some OEMs. Hobbiecolors does not yet have a line of ink color-matched to the 221 type carts, but Image Specialties does. Precision Colours (in Canada) and OctoInkJets (UK), among others, are suppliers of IS inks. All 3 can supply the required 2" long syringes for the Durchstich refill method. Of the 3, only Hobbicolors carries the appropriate chipsetter for the 2xx carts and only OctoInkJets carries the one for the 5xx carts. Precision Colours doesn't think there is one for these cartridges yet (I phoned him). 3. Did I say "reset"? Yes! The encrypted chips that mystified everyone a few years ago are no longer impregnable. With the appropriate chip resetter, you can have your cake -- er, ink monitor, and refill too! (provided you get the right version resetter of course). There are at least 3 different brands of resetter out there -- red ones and blue ones, battery operated and USB powered. One seems as good as the next, by all reports, although for some reason the red ones seem to cost more. I gather they did the original development and the others are clones. 4. There are even auto-resetting chips available, as separate chips or as part of an aftermarket empty cartridge. However, there's a catch with those: They reset themselves when the power is lost. So they may claim the cartridge is fuller than it really is, running the risk of damaging a printhead by running out of ink if you rely on the ink monitor. Also, the printer may run many more purge cycles (possibly because it purges whenever it detects a new cartridge and the self-reset makes the printer think the cartridge was replaced). 5. Counter-intuitively, 3rd party cartridges are frowned upon by many. Apparently the OEM version are better made, using different kinds of sponge materials to keep the air separated from the ink. Also, the ink outlet pad in some 3rd party carts may get in the way of the syringe for the Durchstich refill method. There are reports of people refilling a single cart dozens or hundreds of times (amazing considering the bad old days of refilling no more than twice). OTOH, others report using them quite successfully, particularly when refilling from above. 6. Canon is introducing a replacement cartridge design (CLI-x25 and PGI-x26) with opaque sides to make refilling harder (can't see the levels anymore). When the old stock is gone, the third-party cartridges may more attractive. 7. Pigment black cartridges require occasional purging to flush out accumulated deposits of pigment that might otherwise cause problems. Dye ink cartridges can be refilled indefinitely if not dried out. Dried cartridges should be purged of old ink before use. Purging methods and solvents abound -- everyone seems to have a different favourite. Use the search function and pick one that works for you. 8. Refilled cartridges can be stored awaiting use if they are capped, sealed in a baggie and stored in a cool dry place for no more than 2 years. So, here's my plan: I'm buying syringes and IS ink from Precision Colours, and the appropriate resetter from somewhere else. I'll get one extra set of Canon cartridges so I can always have full spares bagged and ready to go. And I might even consider that extended warranty this time around... My thanks to all the real experts who shared all the above elsewhere in this forum.