The CJs with heat exchangers are still required to use a Biocide (I don't have the reference in front of me, but it's in the AFM) that'll be the 525A and it seems the 1+ and I assume the 2+ and the 3.
The CJs without heat exchangers use it for both fuel biocide and to soak up water.
One of the major problems with it is that if it is not adequately homogenised with the fuel it can clump and those clumps can then block the same filters it was introduced to keep clear.
This problem used to occur on the EBJ fleet with some regularity because we used to use the pouring cans rather than the aerosols.