Use of copolymers comprising alkylene oxide units, which copolymers comprise incorporated randomly or blockwise by polymerization (a) 50 to 93 mol % of acrylic acid and/or a water-soluble salt of acrylic acid, (b) 5 to 30 mol % of methacrylic acid and/or a water-soluble salt of methacrylic acid and (c) 2 to 20 mol % of at least one nonionic monomer of the formula I where the variables have the following meaning: R1 hydrogen or methyl; R2 a chemical bond or unbranched or branched C1-C6-alkylene; R3 identical or different unbranched or branched C2-C4-alkylene radicals; R4 unbranched or branched C1-C6-alkyl; n 3 to 50, as additive to phosphate- and/or phosphonate-comprising aqueous systems in industrial technical plants.