Continous water change

Continuos water change,

Everywhere is (FAQ, articles, etc.)  stated very clear: frequent and small 
amount of water change,  up to 20-30% weekly or biweekly.
What about continuos water change, drop by drop?

I take the water from the toilet reservoir (itís  full of water all the time), 
and drop by drop is coming to my aquarium. I can tune the dropping from 
2g a day up to 20g a day.
My water have no Cl.  The water is going to the tap by an overflow.
Everything is DIY.

It is a good practice?

How many % of my tank should I change daily?
The water is vigorously moving in the tank all the time.

In my opinion in this way itís possible to achieve a very stable 
environment, without pH, CO2 content and other nutrients fluctuations. 
To much tap water could be dangerous? (I have no Cl)

Stefan Tiganas
Romania, somewhere in Europe