Been monitoring/adjusting pH with my TF-100 kit I got about 7 months ago. My original bottle of R-0014 is about used up so I tested using the new R-0014 that came in my refill kit. When using my original R-0014, I get a pH reading around 7.5/7.6 (no expiration date marked on that bottle). The R-14 in my refill kit (exp 4/20) gives me a 7.8 reading. Shoukd I average the 2, only use the newer R-14, or get a another bottle of R-14? Or, is there a way to validate my results?