I've never used a soap type solution in my media so I can't say. But I would be a bit worried about the roots taking soap into their system. But is that any worse than a pesticide?? Since it's S/H you could do it and flush it in a few hours and see it it did the trick I suppose. I myself would add a bit of Malathion to the water and then flush in an hour or two. But the soap is probably less toxic so you could try that first. I have read that Malathion is present in small quantities in creams for people to use when they have scabies or similar skin parasites. So I feel it can't be that bad so long as I am not using it around pets and bees and ladybugs etc.
Hi Greenpassion! I haven't tried Safer Soap or really anything like it. My bug problem is completely gone, though. I tried withholding water until the medium was completely dry, and they all seemed to die off. They haven't returned since I started watering again, either. Best of luck with yours!