I’m currently growing tomatoes, peppers, and tomatoes in coir slabs in fairly small greenhouses. The water amount required varies considerably day to day based mostly on light (other variables are mostly controlled or dependent on light).
Add a light meter, and every time it accumulate a set amount of “lux” a irrigation event is triggered. The lux is light intensity per amount of time. When the sum of this reaches whatever the set threshold is, it triggers a 1-2 minute irrigation event.
I think you would add a number every time the controller reads the light sensor. When that number reaches a set number it triggers an irrigation event and resets to zero
This would be a large improvement as the irrigation controller is responding to conditions the plants are facing. On a sunny day it may need to water 5-10x per hour and a cloudy day 2-5x times per hour.
This needs to based on a local light sensor, because it has to respond to intensity of light. The amount of clouds vary so much over a couple miles or few minutes.