I have a Cuno SQC3 reverse osmosis system. The three obvious filters for replacement on the left are the:
- prefilter - 47-55706G2
- RO membrane - 66-4703G2
- postfilter - 47-55710G2
However, in this picture you see there is a fourth module inline with the water line (on the ground). It doesn't have a identifier on it. Just says "flow" to show direction of water. Does this need to be replaced? Currently my water is coming out very slowly with the filters being 2 years old.