Keep your OEM carts--with TLC they will outlast your printer. I have used OCP inks from rjettek in my Canon 9xxx's for the last decade--with excellent print IQ!!
The ink is available in 4,8,16,+++ oz bottles-small bots go for ~$1/oz--that means ~$0.30 to refill ONE CLI-8 cart. What are you going to do woth all that savings
I have the Mk I and use Image-Specialists bulk ink from ebay. OCP is equally good.
The cartridges are filled by using a syringe to drip into the felt? on the bottom of the cart. Each one takes about a minute.
Image quality is good as genuine carts, but I haven't tested them for UV sensitivity/longevity.
Do fill the carts from the top!! Remove the plastic ball above the 'empty' ink chamber and insert the ink. From Rjettek get the replacement plug to reseal, or thread the ink inlet hole with a 6-32 tap and use a nylon or SS screw. In an emergency a high tack sticky tape will do.
I use OCP ink for mine...excellent quality from a major and long established German company. I also refill the original Canon carts and they are still problem free after two years. As suggested above, remove the 'permanent' ball plugs and replace them with appropriate removable stoppers.
One tip is to always refill all the carts as soon as you need to refill any one of them. The printer thinks it has a new full set. The advantage of this is that it will dramatically reduce the amount of ink flushing as the flushing now only takes place when you insert a 'new set' as opposed to a continual string of individual colours. It will extend the life of the internal ink pads as well.
I calculate that my ink costs are now about 10% that of sticking to Canon carts...I just need to sort out something similar for my R2880....
