I have been taking care of our pool for the past 3 weeks and everything has been going great. However, the sand filter pressure hasn't changed at all. The last time the filter was back flushed was on the 31st of October and since then the pressure has not gone up at all and has been sitting at 16 PSI. I know the gauge is working because when I just circulate the water in the spa the pressure goes up to 22 and then when it is the pool and spa it does come down to 16 again. The gauge was also very recently replaced and seems to work fine. However, I do not see any change. The pool looks good and all my TF-100 results are in my signature. The filter is a Pentair Titan II. Anyway the pool looks great so I am wondering whether I should back flush it or not. The pool guy who was taking care of the pol before I bought the house was back flushing every week and he told me to do the same but I am trying to follow the 25% pressure increase rule. Moreover, I would like to mention that I do not see any major change in the water flow but this is based on qualitative measures, i.e., the waterfall from the spa to the pool seems to look the same as 3 weeks ago. Please let me know if I should just back flush it or wait for the pressure increase. Thanks a lot.