A manifold for a hydroponic system comprises a main body, an inlet port, an outlet port, and an electrical conductivity probe. The main body defines a dosing chamber and comprises at least one dosing port in fluid communication with the dosing chamber. The at least one dosing port is configured to facilitate introduction of dosing fluid to the dosing chamber. The inlet port is coupled with the main body and is in fluid communication with the dosing chamber. The outlet port is coupled with the main body and is in fluid communication with the dosing chamber. The electrical conductivity probe is coupled with the main body and extends into the dosing chamber downstream of the at least one dosing port. The electrical conductivity probe is configured to detect an electrical conductivity of a hydroponic fluid contained in the dosing chamber. A hydroponic system and methods are also provided.