Abstract: A preparation in paste form which contains an s-triazine (I) and a polyethylene glycol/polypropylene glycol condensate or an ethoxylated compound (II) ##STR1## In these formulae, R.sup.1 and R.sup.2 are C.sub.2 -C.sub.6 -alkyl or C.sub.3 -C.sub.6 -cycloalkyl, R.sup.3 and R.sup.4 independently of one another are each hydrogen, alkyl, unsubstituted or substituted phenyl or a C.sub.6 -C.sub.20 -acyl radical, R.sup.5 is hydrogen or methyl, and n is an integer between 1 and 10.The paste is suitable as an algicide for water-containing or solvent-containing lacquer systems, especially for disperse dyes or antifouling paints.