Perhaps I've just been lucky. I use a Kinderman tank and stainless reel which I bought 30+ years ago. The tank is a two reel (2x35mm) PVC tank. When I pour in the developer, I tilt the tank at enough of an angle so that the air can get out while I pour, filling it until the tank overflows. I never tap the tank, mostly because I always forget. Nevertheless, I do not have problems with bubbles.(posted 8167 days ago)FWIW, I agitate by inverting the tank which causes the reel to slide from the top to the bottom since it is a two reel tank with only one reel in it. Perhaps that is enough vibration to shake loose any bubbles.