Biodegradable soap for septic systems?

Hi guys,I have just set up my new septic system using a pair of IBCs and want to
do the right thing and minimise the negative impact the outlet (soak
away) water will have on the environment.
I'm thinking that we really should be using biodegradable washing
products.
I've found biodegradable dishwashing liquid at Woolies, easy, but
couldn't find any similar soaps or handwashes. In fact, the vast
majority of handwashes were ANTI-bacterial, exactly what I DON'T want!
What do you guys use in your septic systems?
Should I be concerned about using regular soaps and stuff?
Thanks in advance,
Greg
.
(BTW, this shot was taken before the system was completely finished and
backfilled etc.)