What's the trick to activating Aquifer Pumping ?

[vigorousRoll]

This is my first game (happens to be a solo). I recently paid for and placed Aquifer Pumping into my tableau and have not activated this blue card yet. No ocean tiles have been placed yet so there are free hexes available for an ocean tile. I have a spare steel die available to pay for the ocean tile. I'm not seeing any prompts above during either the Support Action phase or Main Action phase that would allow me to activate AP. When I click on AP or my spare steel die, nothing happens. And yes, AP is standing straight up, not flipped over on its side. i do see a red arrow on the card leading from a steel die over to the ocean tile but don't know the significance of the redness (as opposed to yellow, say) of the arrow.

What's the trick that activates it?

[Meeplelowda]

This is my first game (happens to be a solo). I recently paid for and placed Aquifer Pumping into my tableau and have not activated this blue card yet. No ocean tiles have been placed yet so there are free hexes available for an ocean tile. I have a spare steel die available to pay for the ocean tile. I'm not seeing any prompts above during either the Support Action phase or Main Action phase that would allow me to activate AP.

The prompts appear on the blue cards themselves. If it is something that can be done during a support action there will be a yellow border around the card you can use and you just click it. If it's a main action card, there will be a red border.

i do see a red arrow on the card leading from a steel die over to the ocean tile but don't know the significance of the redness (as opposed to yellow, say) or the arrow.

This is covered in the tutorial (and the rulebook, of course). If it has a yellow arrow, it can only be used in the support action phase. If it has a red arrow, it can only be used in the main action phase. If it's green, it can be used at any time by clicking the "Free Action" button that will appear at the top when you have that option.

[vigorousRoll]

Thanks. I saw a yellow dotted-line border surrounding Aquifer Pumping and clicked on it for satisfaction.