hi

I’m setting up new P4 system my first venture into aquarium control. My ATO is set up using first 2 sensors which is working.

But struggling to how to set up a manual instigated water change, I would like to start the water change pump via P touch which would turn off if min level in water change tank is low (level sensor 3) ...with a timer just in case. I have an overflow in sump so not to worried about level in sump...although I do have level sensor 4 for alarm if too high in sump.

I have used the maintenance 1 to start the pump but not worked out if I can add level logic to turn off if low..and also been successful setting auto top up.
but struggling with this idea

Any ideas...apologies if obvious but totally new to this and finding it hard going


Many thanks