Thank you all so much for the quick responses!!! I will update my signature with our pool/spa specs and equipment too. The "shock" we used was not chlorine, it was specifically for hot tubs, but I don't have the name of it to memory. I believe it's just simply time to change the water out as it's new to us, our 1st tub to own, and we've had it going since March, and have used it often. So happy to have a positive feedback website to post & get info from. Thank you!!!