Question about Kobre Pond Zierbrunnen Klar

I have used this product against algae and therefore do not know how it works against lime.

I can't say for sure whether it helps against limescale. In any case, the water stays clear and it helps against algae that would otherwise build up on my fountain.
I'm still looking for the ideal product.

I don't know, the water was very clear and not chalky for summertime.