The A905 is a wetting agent of the former east German company „ ORWO“.
The contemporary equivalent (biocides added) should be “Calbe F905”
http://www.calbe-chemie.com/uploads/...ttel%20(D).pdf

Actually you may omit this agent; I introduced it when I switched to development without prewash step.
It looks like there is no real need for it, just a liter on my shelves is waiting to get used before deteroation…

Regards, Stefan