After using my zero water filter for 2 weeks, the water started tasting bad and sour. But the measurements only read 15 compared to the tap water which is over 200. However right now my tap water taste much better

It was time to replace my zero water filter, so we bought a 6 pack of replacement filters from Target. Put a new one in and the water tastes and smells musty like a dark and musty basement.. Its definitely not our tap water as we use two brands of pitchers one Zero water and one Brita. Brita one the water tastes fine. Now what to do if I replace it after only two days with another of the 6 pack, no doubt that one will be the same. Hoping Target will replace them or refund us. We will use the Brita going forward if there is no solution to the mustiness.