I keep coming back to the benefits and the risks....
Benefits: Less effort, more likely to happen,
Risks: If "full auto" failures can be big impact
Due to the risk, I'm aiming for a "semi-automatic" approach...push button, watch it go, address anything that is not the way it needs to be. Keeps all the benefits and eliminates the risks.
Additionally, IMO the 2 primary reasons for WCs are nutrient export and trace element replacement. For nutrient export, I'm not sure it's all that effective unless you "stir sh!t up" (or have a collection point that can be drained). Otherwise you are just taking out very very diluted waste and leaving detritus in your sump to decompose. Today when I do manual WCs, I shake the bag of Seachem Pond Matrix in my sump like a tea bag and put all the settled detritus into the water column.
Thinking peri-pumps would provide accurate volumes, but not move volume fast enough to export significant detritus.
So I'm thinking about a program that would 1) stop return pump 2) kick on powerhead in sump (stir sh!t up) 3) pump out dirty water 4) pump in fresh water 5) restart return pump. The catch is matching the volume of out/in...more so because I have 25' of return and drain line, so the water level in the sump is different from shut down to having enough to refill the 25' return line. Might need to consider more check valves LOL
Anywhose, thanks for sharing!