Not really, just need to compare the actual reading to your set points
For example:
Equal to or Less than [<= Actual My SP1] ----------------( ) //Low Flag
Equal to or greater than [>= Actual My SP2]-------------( ) // Med Flag
etc.
You could add timers (Slugs lol) so that it does not jitter.
So for example:
SP1 Low = 10
SP2 Med = 100
SP3 High = 200
SP4 High High = 250 (or what ever corresponds to your levels.
I suggest you still keep the High High & low low digital signals as alarms just in case the sensor faults and use them as alarms.
You can either use fixed setpoints or have them adjustable on the HMI as an Engineering set up screen.
Yes, rising pressure at the bottom of the tank wrt atmospheric pressure indicates rising level. now you only need to decide what "rising pressure" means.
i.e. filter out noise, sample times, sample size, compare times, how many increasing events means "rsing," etc.
I would suggest something like a moving average (MAVE), say 2Hz sample rate, 10-sample MAVE, check it every 5s or 10s. The actual numbers depend on the in-flow and outflow rates, the size (surface area) of the tanks, the resolution of the pressure sensor, etc.
If the filter or other criteria are too generaous toward making the "rising" call, the alarm will go on and off.