New user - two processes with shared inputs

I'm very new, but learning, so keep it simple for stupid (me).

I'm building a new aquarium, and I want to have automated processes for topping off the water and for draining and re-filling.

I have the basic structure of the circuitry and most of the code down, but I'm struggling with one issue.

When the drain/re-fill process is running, I need the ATO (auto top off) to stop entirely.

I'm on the fence about attaching the drain/re-fill to a clock, and I may just connect it to a button. Regardless, I need to figure out the easiest language to make that input (button or clock) stop the ATO and then start the drain/re-fill. Once the re-fill is complete, I want to start the ATO again.

FYI, they are both based on float switch inputs. The ATO has one pump output and a power head output (moves the water). The D/R has a separate pump.

Using an Arduino UNO.

If more info is needed, let me know.

When the drain/refill process starts, set a flag (disableATO). In the ATO code, check the flag and don’t allow ATO if the flag is set. When the drain/refill process finishes clear the flag to enable ATO.

Thanks, I didn't even see "flags" in my research so far. I'll look that over when I get home from work.

Flag is often used as a synonym for a boolean value, it could be implemented as a bit (with other values in the same byte), usually it is represented by a byte (bool).