Abstract: Water is conditioned by adding thereto a corrosion-inhibiting, concretion inhibiting, precipitation retarding, deflocculating, dispersing or fluidifying amount of an acid of the formula ##STR1## in which R.sup.1 and R.sup.2, independently of one another, represent hydrogen where a or b=1, or where a or b=0 represent an optionally substituted alkyl radical with 1-8 carbon atoms or an optionally substituted phenyl radical,R.sup.3 represents hydrogen, an optionally substituted alkyl radical with 1 to 4 carbon atoms, an optionally substituted phenyl radical, a halogen atom from the group comprising fluorine, chlorine and bromine, a hydroxyl group, an alkoxy group containing 1 to 8 carbon atoms, a carboxyl group or a group --P(O)--(O).sub.a --R.sup.1 OH,R.sup.4 represents hydrogen, an alkyl radical with 1 to 4 carbon atoms, an alkenyl radical with up to 3 carbon atoms, an optionally substituted phenyl radical, a carboxyl group, a fluorine or chlorine atom or a group --P(O)--(O).sub.a --R.sup.1 OH, orR.sup.3 and R.

Abstract: Preventing corrosion and scale formation in water re-circulating systems by adding to the water to be circulated from about 5 to 100 g/m.sup.3, based on the weight of the water to be circulated, of a compound selected from the group consisting of those of the formula ##STR1## and the water-soluble salts thereof and then circulating said water in said system, R being hydrogen, alkyl, alkenyl or alkinyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or ##STR2## wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R'" is carboxyl.

Abstract: In the inhibition of corrosion and scale formation in a water-carrying system wherein to the water there is added a phosphonocarboxylic acid of the formula ##STR1## in which R is hydrogen, an alkyl, alkenyl or alkinyl radical having up to 4 carbon atoms, an aryl, cycloalkyl or aralkyl radical, or the radical ##STR2## R' is hydrogen, an alkyl radical having up to 4 carbon atoms or a carboxyl radical; andX is ##STR3## the improvement which comprises further adding to the water about 5 to 500% by weight of the phosphonocarboxylic acid of at least one member selected from the group consisting of a benzimidazole derivative, polyacrylamide, polyethyleneimine, polyvinylpyrrolidone and lignin sulfonate.

Abstract: Preventing corrosion and scale formation in water re-circulating systems by adding to each cubic meter of the water being re-circulated from about 5 to 100 grams of a compound selected from the group consisting of those of the formula ##EQU1## and the water-soluble salts thereof R being hydrogen, alkyl, alkenyl or alkinyl having up to 4 carbon atoms; phenyl; cycloalkyl having 3 to 6 carbon atoms; benzyl; phenethyl or ##EQU2## wherein R' is hydrogen, alkyl having 1 to 4 carbon atoms or carboxyl, R" is hydrogen or methyl and R'" is carboxyl.