Just experimenting with the big bubble concept. Used 1/2" pipe into a 3" pipe chamber. Added the T to the bottom of the inlet thinking it would allow more of the big trapped bubble to enter. Would have used a 1/2"-2" adapter if I had one instead. Not sure it matters. This adaptation works much better than just sticking an airline at the bottom of a pipe. Big bubbles push more water!

Even better would be to add a swing valve to the inlet as on the geyser pump.