Currently only 90% of air filter cycles return a used filter, and 100% of the used filters can be cleaned.
I think it would work better if 100% of air filter cycles return a used filter, but only 90% of these can be cleaned instead.
The net result is the same (except slightly more dirty water), but it allows using a circuit condition on the removal of the used filter from the purifier. This is crucial for being able to run the drills as long as the purifier is working and stop them when the used filter is unloaded, which helps reducing wasted filters when the storage of a remote mine is full for a long time. Without reliable return of a used filter it's impossible to do this. And I don't see any use in such a setup for the cleaning assembler itself.
I also find this the more logical setup, because I imagine the filter can be reused until it falls apart during the cleaning, it doesn't seem likely that it would fall apart during the filtering. Furthermore this would allow the recycling recipe to show the 90% chance, instead of having to write a long sentence about it in the purifier description.
I know you're not actively developing the mod right now, but it would be nice to add this in the planned future update, since it's such a small change. For now I just made a mini-mod to do this.
if mods["Krastorio2"] then
local recipe=data.raw["recipe"]["restore-used-pollution-filter"]
recipe.results[1].probability = 0.9
recipe=data.raw["recipe"]["kr-air-cleaning"]
recipe.results[1].probability = nil
end
