I have never used a reactor yet, so you need to hear from someone with experience. One thought that comes to mind is maybe you had too much flow going through your reactor, or maybe too coarse (large holes) of sponge on the bottom so small bubbles were being released. I don't know what other people do to get rid of that problem. Does it bother you too much to leave it be? I just added a second bottle of brew to my DIY system today, so I haven't really had time to get used to it yet. It may bother me later, too!