What is the Domino Factor... ?

one of Here is a typical view of the ink levels in a printer, when one of them, in this case its black is showing low ink, that’s the time to replace it and not wait till it went empty, but I wouldn’t just replace the black cartridge. !



As in this Demo Photo, some of the other cartridges are showing at least 30% and more used, this is an ideal opportunity to replace them at the same time too.

Why you ask, well by replacing all the carts at the same time as the black, you'll only get one maintenance purge instead of many, because by the time your printer is ready to print again, one or more of the remaining carts will also show low ink, and so on, its what’s known as the “Domino Factor”.

It’s a false economy to only replace one cart at a time or to run the carts till their empty, you gain nothing by this practice and you must wait ages for the printer to be ready to print again, not to mention your waste ink tank fills even faster.

but the most important things to remember is to never forget to reset the chip before refilling or topping up any cartridge, the resetting of the chip is a major part of proper refilling procedures.

Yes but you should then replace only ink from same group, because purge unit purge only ink from the group where belong. Now you should also count amount of ink used, in mine i9900 service manual says that is about 0.25g per ink. So if I change for example cyan lose will be total 0.81g ( says manual), it purge cyan yellow and magenta. But we already at first must change cyan so total waste is only 0.55g which is not at nearly close of 30% of 13ml tank. (I count that 1ml ink=1g.)

The amounts purged in the PRO9500 are much higher, depending on the color changed from 1,9 to 2.8 ml (per group of 5 cartridges I suppose).
This could also explain why the ink purged in the potty is 2/3 through one and 1/3 through the other outlet.

Additional comment: I observed purge ink coming out of both tubes after changing carts in only one group, meaning either the tubes are not connected to a particular group and only serve to distribute the ink over the (wide) absorption pads, either Canon's group theory is not correctly understood.

The PRO9500 (MK I) was known for it's outrageous ink consumption, the 9500 II uses much less (not documented).
In practice it goes a long way with the carts.
When you use OEM carts, changing all carts together is out of the question, and since refill ink is 5 times cheaper it is not a big concern.
But since you have to refill the carts sooner or later, changing them all together (and refilling the other set immediately) gives the confort of having enough ink.

Hi @palombian, I am glad you brought the ink purging issue up again, because most of the comments in these manuals are false, (Hidden) regards purging.

There is only one purge unit fitted to a Canon printer, it’s all mechanical and there are no electrical or component parts to it, so it has only one way of working, yes there are two tubes coming out but there is still only one pump.

When the unit does a purge, it must cover the bottom all carts, otherwise the vacuum will fail to accomplish its task, but there are several different types of purge it can engage in, a small, a large, and an enormous one. !

These are triggered by many different factors, but by having a Potty fitted you can figure out which type of purge the printer is engaged in and learn to avoid most of the very big ones, this can benefit an OEM user also, after all they are using the most expensive inks.

So, does replacing all the carts at the same time save ink ?, many say YES.
But it’s still up to the individual to make their own conclusions...