Having cleaned many of my LPs using the Knosti fluid, I subsequently found that I was regularly cleaning my stylus to remove quite a lot of dirt. This might be due to several factors: I noticed a build-up of dust and dirt in the brushes and the trough of my Knosti Disco Anti-Stat Vinyl cleaning machine, so I might have inadvertently re-transferred dirt washed off previous records onto new ones. However, having thoroughly addressed that issue by giving the machine a good clean out (the handle of a kitchen wooden spoon is good for dislodging accrued dirt from the brushes without using your fingers), I still found that I was still getting a lot of fluff on my stylus.
So I tried this French-sounding (but German-made) concentrate and found that my LPs came up stunningly clean, non-static and non-dirty - with no build-up of dirt on the stylus. It gives the vinyl an almost slippery feel, which (one imagines) reduces wear and tear on your expensive stylus. My records look more clean, and (unlike the Knosti fluid) there was no discernible odour - a plus if your wife is in the house while you're cleaning your vinyl. Most importantly, my vinyl sounded clearer and more focussed - a purely subjective remark, I know. But having cleaned about 150 LPs with the Knosti and about 100 with the L'Art Du Son, I think I can stand by that judgement. In fact, I'm seriously thinking of re-cleaning the Knosti-treated LPs with the L'Art du Son.
The other advantage is that - being a concentrate - you only need to make up a small amount of dilute solution at a time. There's enough to make a total of 5 litres when mixed with distilled water, so make up 1 litre in a clean screw-top bottle, keeping the concentrate untainted. This should last between 50-100 LPs, depending on how dirty they are. Once the mixture looks discoloured, it's time to make up a fresh mixture. By contrast, Knosti supplies filter papers through which you return their (non-concentrate) fluid back into the original bottle. I think that this is the weakness in Knosti's system: particles contained in the used fluid would get through the filter paper, and thus the fluid becomes more tainted after every cleaning session.
To be fair to Knosti, it certainly cured the static problems I was getting, particularly with some brand-new records. Either way, the moral of my tale is that you should keep your vinyl-cleaning machine regularly cleaned before filling it with whatever fluid - that way, you give your records the best chance of giving you lasting pleasure.