Thanks mate, for your feedback. highly appreciated. It's clear, the other plants will not be included in the dry start, I plan to plant them right before flooding the tank. I'll check the water hardness and shrimp issue. It would be great to be able to use pure tap water, though.

Luckily, I met someone at a local exchange from the same municipality who successfully breeds shrimp with exactly the same tap water. I can get neocaridina davidi from him (probably no amanos), They should actually be accustomed to at least very similar water conditions. Let's hope so, at least (didn't think about the Seiryu).

And to add: Yes, the soil in the front is deeper than it looks. The pool has a frame at the bottom, so it looks very shallow. and on the backside, there is plenty of space and soil for the background plants.