How do I spawn bubbles when swimming?

I have a simple platform game and one of the levels is underwater swimming...

I have a large invisible sprite which is the water... and when the player is 'overlapping the water' the controls/gravity etc. switch to swimming mode.

I'm wondering how to spawn a bubble that rises to the surface every 3 seconds?

I tried 'if player is overalapping water, spawn bubble with bullet behaviour' and ended up with thousands of bubbles (every tick I presume).

So I tried adding a 'wait' for 3 seconds but that didn't work.

Is this because i'm overlapping the water, so it's checking every tick?

I figure this might be simple but i'm clearly missing something.

Thanks for any help, much appreciated :)

Well that worked perfectly (as I'm sure you knew it would!).

Many thanks for that :)