I'm seeking proper pump for my poe water filter, which need min 20 max 125 psi to operate it's auto backwash.

Pump technician quoting grundfos Cm3-4pt(3.5 bars) .
Which I can't find much details about its spec online.
One of the store site stating 18 psi as it's pressure.

1) lack and no details about this product on the official site. No even in any other sites, apart of small pieces spec info .

2) based on my tank pressure requirement, how do I find the proper (grundfos) pump for it?

Just do bypass, cheaper and effective.