Improved flow control valve assemblies for fluid systems (e.g., pools or spas) are provided. Advantageous flow control valve assemblies for pool/spa cleaners (e.g., suction pool/spa cleaners) are provided. The present disclosure provides for flow control assemblies for suction pool/spa cleaners, with the cleaners utilized in conjunction with a variable speed pump. A manual valve set-up can be removed from the system, and an advantageous flow control valve assembly can be provided to automatically regulate the flow/suction to the cleaner. The improved flow control valve assembly thereby provides regulated flow to the cleaner, so that if the cleaner remains in the water at low pump speeds, when the pump is later operated at a higher speed the cleaner will function as designed. When there is flow/suction below the desired operating parameters of the cleaner, the pump will operate as desired, and the cleaner is stationary.