One of the favorites is the black Non-kink spiral pond tubing which is the most flexible tubing and is used with nylon fittings. These fittings are usually found at a pond store. Not only is it very easy to use but can be placed when there is a difficult turn or many turns. Spiral pond tubing has ribs on the outside and is slightly noticeable on the inside. This is one of the most common flexible hoses to use in the pond industry. Even though the tubing is very durable it can develop pin holes even though it is not very common. It is recommended to be buried when using outside of the pond. This tubing is usually used underwater with a submersible pump and then up to a waterfall or filter. Fittings are secured with clamps.