Sorry about the confusion, and please forgive my inexperienced ignorance. I assumed that most aquarium air lines, such as what you would buy at a pet store, were generally the same diameter. The same thought on most of the water pumps I've purchased. Anyway, I was going to try to push a little water through some dead spots behind my live rock, and I didn't want to use the thicker tubes that normally attach to the water pumps. I figured air line would be less noticeable in the display. However, I found out that Marine Depot carries all the Loc-Line accessories I would need to direct the flow from the return nozzles. They even have inline valves to adjust the flow rate. I thought that was awesome, so I ordered a bunch of parts. Fun stuff.