I only use a water level occasionally, so rather than buying a long length of vinyl tubing that would then sit on a shelf somewhere largely unused, I decided to simply adapt my garden hose to the task. To do this, I fitted the hose out with a pair of threaded hose barbs, which are readily available at any hardware store and cost only a couple of dollars each. The fittings – which can be made from either brass or plastic (which is a lot cheaper) – have a male or female thread on one end (you’ll need one of each, sized to fit your hose – typically 3/4 inch) and a serrated barb on the other that can be inserted into flexible vinyl tubing. I bought fittings with 3/8-inch barbs, but other sizes are available depending on the size of vinyl tubing you have on hand. You won’t need much; a length of a foot or so at each end works fine.