Sorry but I'm not certain what a wilma is, but for my aero setup I use ONA bleach. It comes in two parts, you mix the two, let them set for 10 minutes then add then to the res and run the pump.
I do this after scrubbing all the left over plant material and do a general good clean prior to the bleach. This bleach solution will clean spaghetti lines and dissolve salt build-up in the system. This will be my 4th grow in this system and I've had no problems so far!