Mixed ratio during descaling - Gaggia coffee machine

Good evening here at the Forum,

I'm new here, registered to get rid of a question that's been on my mind for some time. I have, as described above, a Gaggia machine as a second device. The part has been on the hump for some years, but still does its job well without grumbling.

My question relates to the decalcifying process, as indicated. My decalcification product indicates to mix 100 ml with 400 ml water. The decalcification program of the machine, however, requires a residual quantity of approx. 900 - 1000 ml of liquid for the entire process. Do I now take 200 ml decalcifying liquid and mix with 800 ml water to get the same mixing ratio and leave it at 100 ml and fill up the rest with water?

Maybe a stupid question, but I would still appreciate a professional reply. Thank you very much.

Many greetings