As a field tech I have found that at several facilities I have recently visited the pump room maintenance staff have seemed to ignore the fact that they have no flow meters on their bypasses. Or they have flow meters that are not working properly on main plumbing lines & bypasses. I have also found that these same maintenance staff strangely enough ignored my advice on the matter on previous visits to these very same facilities.
Having properly functioning flow meters is instrumental for the proper operation of all the equipment within a pump room.
For instance, chlorine generators & UV systems which often are installed in a bypass configuration will have optimum flow rates that allow these systems to function at their manufactured design limits for chlorine production & pathogen kill rates.
Other equipment such as sand & cartridge filters have minimum & maximum flow rates. Not following these recommendations can put strain on circulation pumps, equipment and the plumbing itself.
Flow meters allow bypass valves & variable speed pumps to be set at positions for optimal performance.
Today flow meters and pressure gauges can be digital and can connect to a number of premium chemistry controllers providing serious operators with yet another level of data remotely, to better ensure the correct function of the pools.