[AbiDrew85]

To adapt to the different sizes, you need both sizes of plastic (silicon) tubing and a barbed pipe adapter. I couldn't find a single piece, but this pair screwed together from Home Depot would do the trick. You will need a bit of teflon plumbing tape to put around the thread to make a proper seal.

There're pipe and tubing supply warehouses with online shops you can buy most barb interchanges from, including ones that are all one piece, which decreases the number of possible points of equipment failure.

Sourcing things when you want to be able to go to a brick and mortar can be more challenging, always.