Cistern for garden irrigation - Which pump?

I personally now know three installations with the Tipp (AUT). They have been running without problems for years.

Are the pumps simply placed on the bottom of the cistern? This is actually a pump for a well. Some pumps have a "frame" so that the pump stands a little elevated or a float for floating extraction. Or install the pump hanging by the rope?

I have the Gardena and it is hung just above the ground by a rope.

Hang just above the ground by rope or chain.

Currently, the lid of the cistern is still below the height level that the garden will/should later reach. Are there any extension rings or a nice attachment for that? Does anyone have anything? I have understood the rest so far. I will now measure all the necessary lengths and then order everything. It should be doable.

Why do you want to use a huge deep well pump in a cistern? I would opt for an automatic submersible pressure pump here. These are also significantly less sensitive than pumps with 7 or 8 stages. I would recommend the Gardena 6100/5 inox. It can also optionally handle floating intake and is available for just under €250 and comes with a 5-year warranty.

There are extension rings or telescoping roof shafts.