[walkingfish]

I have noticed that problems of foam in bioreactors seem to be addressed in one of two ways:

Either there is a foam detector that, when it detects foam, dispenses an anti-foam agent into the bioreactor, or anti-foam agent is fed through a drip feed into the reactor.  Both of these methods add small quantities of anti-foam agent at a time.  Why do this?  Why not just add quite a bit of anti-foam agent to the media right from the start, so it doesn't have to be added again later?  Of course, TOO MUCH couldn't be added.

Let's say, though, that by dispensing drops of anti-foam agent, at the end of the run a total of 30 mL of anti-foam agent were dispensed.  Why not start the run by adding 30 mL of anti-foam agent?