auto top up

Noob question: do I need to switch off Tunze Osmolator 3155 which is connected to a sump when doing WC? Logically yes but I thought I check.

I've tried Smart ATO in the past but it didn't work well. Whenever I tried to get the pump to push the water through the sump, it just constant beeping ... I got a feeling the pump is not strong enough for the head pressure. I'm after a reliable ATO top up system with strong pump, strong...