The present invention relates to a method of inhibiting the growth of
killing algae, bacteria, yeast and/or fungi in a recirculating water
system which comprises adding to the water a polymeric biguanide and an
adjuvant of the Formula (1) or a salt thereof:
##STR1##
wherein:
R.sup.1 is an optionally substituted C.sub.8 to C.sub.12 or C.sub.18 to
C.sub.22 alkyl group; and
R.sup.2 and R.sup.3 each independently is H or optionally substituted
C.sub.1-4 -alkyl.
