A process for inhibiting scale produced during wet process phosphoric acid production, the process comprising adding a scale inhibiting amount of a reagent to at least one stage of a wet process phosphoric acid production process, said reagent comprising a reaction product having a weight average molecular weight ≤ 1 kDa and at least one primary amine, wherein said reaction product is characterized as the product between Reactant A and Reactant B, wherein Reactant A comprises a polyamine or polyether amine selected from the group consisting of diethylenetriamine; triethylenetetramine; tetraethylenepentamine; dipropylene triamine; diaminoalkanes; dimethylaminopropylamine; diethylaminopropylamine; bis(3-aminopropyl)-methylamine; 3-(2-aminoethyl)amino-propylamine; N,N'-bis(3-aminopropyl)-ethylenediamine; neopentanediamine; isophorone diamine; aminoaniline; aminomethylbenzylamine; 4,4'-diamino-dicyclohexylmethane; 3,3'dimethyl-4,4'-diamino-dicyclohexylmethane; 3-cyclohexylamino-propylamine; 4,7-dioxadecane-1,10-diamine; and 4,9-dioxadodecane-1,12-diamine; and wherein Reactant B comprises a hydrocarbyl radical having from 1 to 22 carbon atoms and an amine reactive group, wherein one or more carbon atoms of the hydrocarbyl radical is optionally replaced by a hetero atom, and/or optionally substituted at one or more substitutable position with a substituent selected from the group consisting of OH; C 1 -C 12 alkyl; C 1 -C 12 alkenyl; allyl; halogen; C 1 -C 12 haloalkyl; C 1 -C 12 alkoxy; hydroxy C 1 -C 12 alkyl; carboxy; C 1 -C 12 alkoxycarbonyl; C 1 -C 12 carboxyalkoxy; C 1 -C 12 carboxamido; cyano; formyl; C 1 -C 12 acyl; C 2 -C 12 alkyl ester or alkylhydroxy ester; C 6 -C 12 aryl ester; nitro; amino; C 1-12 alkylamino; C 1-12 dialkylamino; anilino; mercapto; C 1-12 alkylthio; sulfoxide; sulfone; C 1-12 acylamino; amidino; aryloxy; arylamino; amido; epoxy; carbonyl; alkoxycarbonyl (ester); nitrile; ureido; silanol; phenyl; benzyl; heteroaryl; heterocycle; phenoxy; benzoyl; benzoyl substituted with amino, hydroxy, methoxy, methyl or halo; benzyloxy; and heteroaryloxy, provided that Reactant B includes at least 4 carbon atoms, which can be cyclic, linear, or branched, with the proviso that said reagent contains less than 50% by weight of an oil and wherein the reaction product of Reactant A and Reactant B is less soluble in an aqueous solution of the wet process phosphoric acid production stream than Reactant A alone. adding a scale inhibiting amount of a reagent to at least one stage of a wet process phosphoric acid production process, said reagent comprising a reaction product having a weight average molecular weight ≤ 1 kDa and at least one primary amine, wherein said reaction product is characterized as the product between Reactant A and Reactant B, wherein Reactant A comprises a polyamine or polyether amine selected from the group consisting of diethylenetriamine; triethylenetetramine; tetraethylenepentamine; dipropylene triamine; diaminoalkanes; dimethylaminopropylamine; diethylaminopropylamine; bis(3-aminopropyl)-methylamine; 3-(2-aminoethyl)amino-propylamine; N,N'-bis(3-aminopropyl)-ethylenediamine; neopentanediamine; isophorone diamine; aminoaniline; aminomethylbenzylamine; 4,4'-diamino-dicyclohexylmethane; 3,3'dimethyl-4,4'-diamino-dicyclohexylmethane; 3-cyclohexylamino-propylamine; 4,7-dioxadecane-1,10-diamine; and 4,9-dioxadodecane-1,12-diamine; and wherein Reactant B comprises a hydrocarbyl radical having from 1 to 22 carbon atoms and an amine reactive group, wherein one or more carbon atoms of the hydrocarbyl radical is optionally replaced by a hetero atom, and/or optionally substituted at one or more substitutable position with a substituent selected from the group consisting of OH; C 1 -C 12 alkyl; C 1 -C 12 alkenyl; allyl; halogen; C 1 -C 12 haloalkyl; C 1 -C 12 alkoxy; hydroxy C 1 -C 12 alkyl; carboxy; C 1 -C 12 alkoxycarbonyl; C 1 -C 12 carboxyalkoxy; C 1 -C 12 carboxamido; cyano; formyl; C 1 -C 12 acyl; C 2 -C 12 alkyl ester or alkylhydroxy ester; C 6 -C 12 aryl ester; nitro; amino; C 1-12 alkylamino; C 1-12 dialkylamino; anilino; mercapto; C 1-12 alkylthio; sulfoxide; sulfone; C 1-12 acylamino; amidino; aryloxy; arylamino; amido; epoxy; carbonyl; alkoxycarbonyl (ester); nitrile; ureido; silanol; phenyl; benzyl; heteroaryl; heterocycle; phenoxy; benzoyl; benzoyl substituted with amino, hydroxy, methoxy, methyl or halo; benzyloxy; and heteroaryloxy, provided that Reactant B includes at least 4 carbon atoms, which can be cyclic, linear, or branched, with the proviso that said reagent contains less than 50% by weight of an oil and wherein the reaction product of Reactant A and Reactant B is less soluble in an aqueous solution of the wet process phosphoric acid production stream than Reactant A alone.