I have been struggling for some time now to find out how much ink is going in the maintenance ink tank, when is it happening and what is the the best practice to avoid it.
I bought a scale with good accuracy of +/- 0.03 grams and started measuring how much ink is going in the waste tank in different situations. I must point out that all the data I will provide is in grams, not milliliters. I guess they are close enough as measuring empty and full ink cartridge is about 84-86 grams difference.
The data is collected with 2.040 firmware version. With any new version there may be changes made by Canon and the data provided will no longer be accurate.
So, it all started when I got the idea to leave the printer always On, so that I can skip the initial maintenance on every power up.
I had 11 days without printing and I left it on for that time, disabling Auto power OFF in the settings.
The result was that one of the black heads developed slight clog and there are some lines, which were not so crisp in the nozzle check pattern. There were also some white lines on the black rectangles before every grid, indication a clogged nozzles. So I performed 2 cleaning cycles to get rid of that clog.
Normal Cleaning Cycle ink usage: 8.2 gr. In my case 16.4 grams for two cleanings.
There are some details I need to point out about what I learned from the tests so far. The printer has a timer that is zeroed on every print. It has at least two maintenance events I have found so far. First is how many hours from last print power on maintenance. The second is how many hours from last print before/after print maintenance. Executing power on maintenance does not clear any counters! If you make 10 power on/off in sequence it will waste ink every time, no matter how much time there is from previous power on/off. Only a print resets the counter. Nozzle check is also a print, so it resets the counter.
Measure the power on wastage, without printing, measuring it every day.
Procedure: I measure the waste ink tank, powered on and then powered off the printer and measure again.
On after 0-4h: 0 grams
On after 4h+: 0.11 grams
On after 5h+: 0.15 grams
On after 6h+: 0.9 grams
On after 24h+: 1 grams
On after 2-3 days: 2 grams
On after 4+: 3.2 grams
Here are the numbers for printing after different period of time from last print. This numbers do not include the 0.05grams that are flushed after every print and are mandatory:
Print after 0-6h: 0 grams
Print after 6h+: 0.9 grams
Print after 12h+: 1 grams
Print after 24h+: 2 grams
Print after 2d+: 2 grams
Print after 3d+: 3.17 grams
Print after 11days: 3.3 grams
On every print, the printer wastes 0.05 grams NOT 0.3 grams as widely spread information in forums. Maybe it used to use 0.3 grams, but not anymore, I do not know.
On every false page feed (if you print from rear tray for example, but put the paper in manual feed) it also wastes 0.05 grams, no matter that it never printed anything.
I was pleasantly surprised that the printer uses NO ink on cartridge change! Tested with two cartridge changes.
So if you print and power off the printer and then power it on and print after 4 days an 1 minute the printer will waste 3.2 grams on power on, then ~3.2 more for first print and 0.05 for every other print.
So, considering the following information, if one is planning to print at least once per week, the printer better stays on all the time disabling auto power off function.
I will travel soon for 20+ days and will measure what is going on after that and post again.
There have been some suggestions that the printer is also counting how much printing (square meters) it has done and activates more cleaning jobs after some number, but I have no evidence for such actions so far.
I may measure how much other cleaning modes cost, but not before I need them, as I spent too much money so far for getting this information.
I returned from my trip and I’m very happy to report some good news.
There were some frightening information circulating on the net that after 45 days of inactivity the printer will suck about 50mg of ink, but this is not the case with firmware 2.040!!!
The printer suck the usual 3 grams on power-on and 3 more on first print. The Nozzle check test looks perfect, like I left it.
So the table looks like this:
On after 0-4h: 0 grams
On after 4+: 0.11 grams
On after 5+: 0.15 grams
On after 6h+: 0.9 grams
On after 24h+: 1 grams
On after 2-3 days: 2 grams
On after 4+: 3.2 grams
On after 48 days: 3.16 grams
Here are the numbers for printing after different period of time from last print. This numbers do not include the 0.05grams that are flushed after every print and are mandatory:
Print after 0-6h: 0 grams
Print after 6h+: 0.9 grams
Print after 12h+: 1 grams
Print after 24h+: 2 grams
Print after 2d+: 2 grams
Print after 3d+: 3.17 grams
Print after 11days: 3.3 grams
Print after 48 days: 3.3 grams
I did find one unreasoned ink waste on one print before my absence, but didn’t find time to report.
After printing 4 pages A3 Luster media I measured nearly 5 grams waste. On one of the prints I got asked to change GY and got long ink agitating after that. I wander if this waste was because an ink finished in printing or because of some maintenance schedule based on area printed. The printed page was not interrupted. Next time I get this unexpected waste I will count the printed square meters and wait to see if there are some rules I can discover. This is for now.
Bad news.
With firmware 2.050 I started a print today and was asked to change the maintenance cart (MC) after that there was about 6 min different noises and I got 58grams in the MC. 
Men that hurts!!
I also experienced power loss for several hours as the power grid went off two days ago for the whole night and my USP run out of battery.
So the questions are: Do we get this cleaning activated on every new MC? Do we get this cleaning after power loss? Will this cleaning happen if we change the MC before requested by the printer?
Next things to test:
1. is to unplug the printer from the wall socket for one night and see if it will get the 58 grams and if not maybe we can add 58g ink price to the price of the MC.
2. Change MC before it is full.
So after all maybe it’s not about days off…
Here is a video how 58g waste looks and sounds like:
Here are some new findings.
In the menu of the printer there are tree setting regarding auto cleaning.
1. Auto nozzle check, which checks the nozzle after every print and performs a little clean whenever it wants without any visible problem with the nozzles. I have not confirmed wasted quantity, but judging from the different time to clean it must be variable from 0.05 to almost a gram…guessing. I have disabled mine and printed hundreds of prints without problems with nozzles clogging … so far.
2. System cleaning frequency: cannot be disabled, I set mine on standard.
3. Ink maintenance. This setting is responsible for time related maintenances! After disabling it the printer does not perform the time related ink waste that I described in my previous posts!! I’m using this mode from 27th of may without any problems with biggest pause between prints 2 weeks. After this two weeks on first print the printer wasted only 2.5 grams and did agitation of the inks. After several days inactivity I’ll repeat this conditions to see if it is time related or just print volume related.
There were some posts that the printer uses small amount of ink on regular bases if left ON, but I cannot find any evidence of that and I seriously doubt it. In fact every time the printer performs some cleaning it make specific sounds, but I have never heard the printer do even a slightest move on it’s own while staying on all the time.
So, with 1 and 3 maintenance settings off, the printing waste looks something like this.
Small prints 10x15cm about 0.07g per print fixed. This includes small maintenance on every 4-5 prints. Without this maintenance with firmware 2.050 the amount dropped from 0.05 to 0.03 grams.
A3+ size wastes about 0.12 grams on every sheet.
There is one more waste that is not included in the above numbers as I have not found out when it appears. It is about 4.8 grams on every 80-100 10x15cm prints. I have not found out on other media sizes yet, but I’m watching for the next waste to try to find something to relate it.
And finally some of us has suffered the system clean of about 58grams that happens at least once per ink set. So calculating this huge waste I will not be surprised of 0.3 grams (as suggested by other knowledgeable fellas) per print is even less than the reality…
All this testing unfortunately require time and having something to print 
I will report when I have new info…
For 16 days and 15 hours the maintenance cartage has lost weight from 397.12 grams to 392.88. This is 4.23 grams evaporated on 25C temp. If some cleaning is happening when printer is on as explained by canon to a customer, it is so small that it definitely is not reaching the maintenance cartridge.1.with the printer ON, I turned it off to see what will happen when I turn it on again: 0.03g. after off, 3.24g after on again and also we got ink agitation.
2. 2nd off/on to check if it will perform that again: yes it did but without the agitating ink routine. So it’s save to say that this can be stopped only with printing something.
3. Print Nozzle check: Perfect test page (after two off/on cleanings anyway), but the printer also performed cleaning of 3.28g before printing. If I have not been testing on/off, that was going to be the only waste.
4. After nozzle check print I was asked to change the CO cartridge. The printer did agitating inks routine after CO change and no waste was measured after the printer was ready. So far I have changed several cartridges and the printer has never used ink on cartridge change.
So it seams that even with the “Ink maintenance” turned off, the printer is performing some mandatory ink maintenance on long pauses without printing. Now I have to find out how long is the pause, so that I can print something before the 3g timer kicks in and I think this will be the end of my tests for least maintenance waste owning this printer.