A method of producing bimodal ethylene-based polymer comprising: reacting ethylene monomer and C 3 -C 12 α-olefin comonomer in solvent in the presence of a first catalyst in an agitated solution polymerization reactor to produce a first polymer fraction; outputting effluent from the agitated solution polymerization reactor, wherein effluent comprises the first polymer fraction, unreacted ethylene monomer, and unreacted C 3 -C 12 α-olefin comonomer; adding a second catalyst to the effluent downstream of the agitated solution polymerization reactor and upstream from a non-agitated solution polymerization reactor, wherein the second catalyst facilitates further reaction of the unreacted ethylene monomer and unreacted C 3 -C 12 α-olefin comonomer to produce a second polymer fraction having a density and melt index (I 2) different from the first polymer fraction and the second catalyst and effluent mix in at least one mixer downstream from the agitated solution polymerization reactor and upstream of the non-agitated solution polymerization reactor; passing the second catalyst, second polymer fraction, and the first polymer fraction to the non-agitated solution polymerization reactor; and passing additional ethylene monomer, additional C 3 -C 12 α-olefin comonomer, and solvent to the non-agitated solution polymerization reactor, wherein the additional ethylene monomer, additional C 3 -C 12 α-olefin comonomer react in the presence of the second catalyst to produce more second polymer fraction and thereby the bimodal ethylene-based polymer, the bimodal ethylene-based polymer comprising the first polymer fraction and the second polymer fraction. reacting ethylene monomer and C 3 -C 12 α-olefin comonomer in solvent in the presence of a first catalyst in an agitated solution polymerization reactor to produce a first polymer fraction; outputting effluent from the agitated solution polymerization reactor, wherein effluent comprises the first polymer fraction, unreacted ethylene monomer, and unreacted C 3 -C 12 α-olefin comonomer; adding a second catalyst to the effluent downstream of the agitated solution polymerization reactor and upstream from a non-agitated solution polymerization reactor, wherein the second catalyst facilitates further reaction of the unreacted ethylene monomer and unreacted C 3 -C 12 α-olefin comonomer to produce a second polymer fraction having a density and melt index (I 2) different from the first polymer fraction and the second catalyst and effluent mix in at least one mixer downstream from the agitated solution polymerization reactor and upstream of the non-agitated solution polymerization reactor; passing the second catalyst, second polymer fraction, and the first polymer fraction to the non-agitated solution polymerization reactor; and passing additional ethylene monomer, additional C 3 -C 12 α-olefin comonomer, and solvent to the non-agitated solution polymerization reactor, wherein the additional ethylene monomer, additional C 3 -C 12 α-olefin comonomer react in the presence of the second catalyst to produce more second polymer fraction and thereby the bimodal ethylene-based polymer, the bimodal ethylene-based polymer comprising the first polymer fraction and the second polymer fraction.