A method for depositing a zinc-nickel alloy on a substrate, including:



(a) providing the substrate,
(b) providing an aqueous zinc-nickel deposition bath as catholyte in a compartment, wherein the compartment includes an anode and anolyte, the anolyte being separated from catholyte by a membrane, and the catholyte includes nickel ions, complexing agent, zinc ions,
(c) depositing zinc-nickel alloy onto the substrate, wherein after step (c) nickel ions have lower concentration than before step (c),
(d) rinsing the zinc-nickel coated substrate in water, obtaining a rinsed zinc-nickel coated substrate and rinse water including a portion of the complexing agent and nickel ions,
wherein (i) a portion of rinse water and/or a portion of catholyte is treated in a first treatment compartment to separate water from the complexing agent and the nickel ions,
(ii) returning the separated complexing agent to the catholyte, and
(iii) adding nickel ion to the catholyte.