I am dumb, I dont understand how to set up a filter in integrated dynamics

I want to automate making uranium for my reactor and Im almost done, already automated autocrafting the uranium dust and smelting it, however the thing Im having a problem with is trying to filter redstone into my centrifuge but with the condition to always have some in my network so is always available. In the second image I already managed to create a variable card that checks if the item is less than the ammount I want on the network however the only place I can put this is is in the export all item place, which I dont want so I dont accidentally export something that isnt redstone into the centrifuge. Can you help me? Is there an element Im missing to achieve this?