by Rob, July 26, 2008
The Trio for Clean and Clear Pool Water - Remember the Trio necessary for clean and clear pool water: Filtration, Circulation and Sanitation.
Today we look at Part II of the Trio, Circulation.It was pointed out last month that if you had the circulation of a rushing river, moving your water at say, 1,000 gallons per minute, you likely wouldn't need filtration or sanitation. I guess algae can't grow when it's moving so fast. But our little pipes and little pumps just can't handle 1,000 gallons per hour, can they?
Most builders will design their in-ground pool circulation systems to pull water from the surface and from the bottom - push it through a filter, and then return the water to several areas around the pool. The idea is to prevent dead spots, or zones where the water can become nearly stagnant.If your in-ground pool does not have a main drain, (or no longer does) and you are only pulling water from a surface skimmer, deep areas of the pool can become cloudy, and make it easier for algae to bloom. An automatic pool cleaner can be used to compensate for the lack of a main drain, or return fittings can be angled down, to "sweep" through the deep end.
If your pool does not have a skimmer - keeping the surface clean can present a challenge. For many pools, using a lily pad skimmer, or an Aladdin No-Niche Skimmer is a easy solution. Having both a skimmer and a drain is useful for proper pool water circulation.
Most pools have 2 or 3 returns, placed in areas as to create a circular flow pattern. Some pool builders will bring the return pipes through the wall at an angle, designed to facilitate this circular flow pattern. Others will use directional eyeball fittings to angle the returning water down to the bottom or towards one end of the pool. Your returns should not be pushing water in opposite directions, which will create competing flow patterns - in the same direction, creating a synergistic flow in one direction, around the pool. I like to use street 90's to get the returning water flowing right along the walls, following the curve of the deep end.
Another advantage of creating a circular flow pattern, just below the surface, is that it keeps your pool cleaner. By creating a slight surface action, the leaves and debris on top are repeatedly brought around the pool, in front of the skimmer, where they can be skimmed off before sinking to the bottom. Health departments commonly use a non-toxic dye to test the flow patterns in pools they inspect. After adding the dye, they wait to see that the dye reaches all areas of the pool, to ensure there are no dead zones - where the water may be less sanitary.
Valve adjustment can help to improve pool water circulation as well. Larger in-ground pools may have dual skimmers and a main drain. By reducing the flow from skimmers that are closer to the pump, balance can be achieved between two or more skimmers. Partially closing the valves controlling closer skimmers will allow the pump to pull more water from skimmers located further away. Most pools do not have valves controlling the returns, but if yours does, then restricting flow to closer returns will balance the flow, allowing more water to flow out through returns located further away from the pump.
So, in summary - Circulation is one of Three important components necessary for clean, clear pool water. It's worth taking a look at this summer, to make sure that your circulation is optimal. Why? Because all three components work together -Increased circulation means that your pool will require less $anitation, and less filtration time means you can run the pump le$$.
Next time, we'll take a look at the finer points of Sanitation. Until then – happy pool-ing around!