Flow meters are designed to measure how quickly water travels through a filtration system. This is useful for all sorts of recreational water facilities. Pools and spas have been using them for years. Often times health departments will require them for float tanks, as they help provide a certain level of assurance to the filtration quality of a system. 

The problem arises when using flow meters that aren't designed to handle the specific gravity of float tank solution. So far, only one flow meter is designed to be accurate for float tanks and if a system isn't using that one, it can be a bit surprising to find out that the flow is different. Ashkahn and Graham talk all about the reason for flow meters and how to troubleshoot problems that may cause a loss of flow.