David;

Most SWCG's sold in the USA do not have the capacity to fully chlorinate an outdoor pool unless stabilizer levels are greater than 20ppm. I have no info about "Aqualux Dynamic" products (a French brand, I assume?), but I would guess your case is similar.

So, you want to have enough CYA present, without too much. I'd recommend finding the manual for your unit and following the recommendations there.

Otherwise, much of what I would tell you to do is dependent on your use of pool test kits not available in Europe. If you want to look around, some comprehensive Palintest and Lovibond pool test systems are available. They are better than test strips, though much more expensive, and not as accurate, as the Taylor K2006 we recommend.