Uhm, this maybe a stupid question, but how do you figure out what your flow rate is? I have a 2-speed pump.

I notice that my flow rate drops when the DE filter needs a cleaning (showing ~10 psi higher backpressure at that point compared to when it's clean).

Quote Originally Posted by Poolsean View Post
The flow switch that we use is rated for 13 - 15 gpm minimum flow. Actually the specs indicate that the flow switch will deactivate at around 13 gpm, but may require 15- 19 gpm to fully activate. Having said that, it's difficult to specify what the minimum flow is other than giving you a general answer of "make sure you've got at least 20 gpm minimum".