Circuits - how do I total the signals of the same type and different quality?

[Mad Inventor]

My use case:
I have an upcycling setup that moves all the ingredients of one product on a sushi belt. These are mixed quality since they are output from producing and recycling the final product with quality modules.
I have dedicated belts that bring in new ingredients, each of those belts carries one type of ingredient.
What I want to do is limit the input of new ingredients from each of those belts if the total amount of that ingredient (total of all quality levels) on the sushi belt is over a maximum.
I've tried setting enable/disable conditions for the belts and for inserters, but it doesn't allow you to use "any quality" when setting a condition, you can only read one quality level of one signal.
So I want to total, for example, all the mixed quality refined concrete on the sushi belt and send that as one signal to the belt/inserter that brings in refined concrete. So if there is more than 200 refined concrete of all qualities, for example, the inserter or belt adding refined concrete is disabled.
This way, I can make sure there is some space for each ingredient on the sushi belt.
I've tried using the selector combinator's quality functions but I don't really understand what they do. Arithmetic combinators seem to only read one quality level of a signal. Decider combinators can have multiple conditions set to check different signals (thus different quality levels) but I'm not sure how to total the output into one signal.

[robot256]

Once you get a wire with all the qualities of concrete as separate signals (either with selectors, deciders, etc), connect it to an arithmetic combinator set to "EACH + 0 --> A" for example. Every signal will be read and output onto A, so A will be the sum of all of them.