II. Circulation & Turnover

Circulation refers to the process of regularly moving all of the pool water through the pump and filter system. In contrast, the term turnover is used to describe how long it takes for a given amount of water to pass through the pump. In other words, when it is said a pool has an eight hour turnover it simply means that when the pump is running it will take eight hours for the net volume of water in the pool to move throught the pump and filter system.

It is important to note that turnover does not mean that all of the water in the pool went through the pump and filter. It could be the same water over and over, which is what happens when water is not properly circulating. The growth of Black Algea can be evidence of slow or "dead spots" in the pool that occur because of poor circulation to those areas causes insufficient amounts of sanitizer or algaecide to reach those areas frequently enough to be effective.

There are several things you can do to help assure proper circulation. If the pool has a bottom or main drain, keep it open so that at least 50% of the water is being drawn through it. The skimmers then handle the rest. Adjust the return line fittings so that they direct the water flow in a generally circular patter around the pool and also aim them gently downwards to improve water mixing from top to bottom. This last point is critical in pools with no main drain or where the main drain no longer functions due to age or some other problem that is unable to be corrected.