Water tubes are essential to holding down your pool cover. They serve as extra protection to keep your swimming pool cover above your pool and not in it! Blue Waves 8 ft single chamber water tubes are composed of rugged 18 gauge material and will not split like thinner 14- or 16-gauge bags. The high quality Halkey Roberts no-leak valves are easily filled with a garden hose. Up to 33 percent heavier than other bags, these tubes will stand up to the competition!