Which product should I get for a timer that turns on/off power?

I'm wanting to turn a water pump on for 15 seconds and then turn it off for 3 minutes... and then repeat that continuously until I turn off the whole operation.

What Arduino product is best for this?

Hi,
Any Arduino (UNO easiest) should work. Then you can set various timings, controls etc.

Then have it control power with optically-isolated relay board like THESE


More info HERE

DISCLAIMER: Mentioned stuff from my own shop...