New pool owner here.
I have a Pentair FNS Plus filter, but do not know the filter size. On the side of the filter, there is a chart where the person installing the filter was supposed to 'check off' the model number (see below). As you can see, no one did this.
The person that was "maintaining" the pool said she was told to add 6 cups of DE after backwashing. Yet, when I look at the filter, the minimum size listed is 36ft, which would call for 8 cups (based on the chart on the bag of DE).
Is there a way to tell what the filter size is for sure?