I see you modified the ATO . I have this exact same sump except I am still using the original ATO its kind of annoying haha and not 100% reliable part of which is my fault because I don't constantly blow out the line or wiggle the float valve
Super curious to see what you did to fix this and how reliable an ATO it is
APEX ATO connected to a 25 gallon freshwater tank in basement via airline tubing.
Use an Avast diaphragm pump (this is super reliable and trouble free).
The fresh water tank has high/low optical sensors that activates a solenoid valve on RO/DI unit.
This part of my setup has been working well for me.