The science of Hydraulics is the study of liquids at rest and in motion. To design an efficient filtration for a swimming pool or spa, we must know hydraulic principles. Poorly designed and installed systems create excessive friction losses, which wast energy and money. In a swimming pool filtration system we are concerned with the movement of water from the pool, through the pump, filter, and heater and back to to the pool. To design a proper filtration system many things must be taken into consideration. Most importantly the Turnover Rate. The turn over rate is the time it takes to filter all the water one time. Ask the salesman you are interviewing what the turnover rate will be for the pool they just designed.

Most pool equipment manufactured today does a good job at meeting the minimum turn over rates. The problem is that many pool builders just turn over a pile of PVC pipe and fittings to the lowest bidder, usually someone with no formal training in hydraulics or plumbing, and he goes about digging trenches and gluing pipe together. Visit a swimming pool jobsite and ask the "plumber" to show you his calculated plumbing schematic. Ask if thought was given to calculating things such as head loss, friction loss, total head curve or the most critical of all "turnover rate". Did you know each 90 degree elbow used on a 2" run will add the equivalent of 5.7 feet of friction loss? Most plumbers don't know this either or just don't care. It is usually left up to the unsupervised sub contractor to wing it. Using too many 90's to make up for poor pre planning will have an impact on turnover rates. Poor turnover rates will have a big impact on how difficult your swimming pool will be to maintain. If you want a green pool all summer ignore this critical information and let your builder just wing it. If your salesman can't explain basic hydraulics to you, you probably have the wrong pool company bidding your job.
Here are some examples of what a swimming pool plumbing installation should NOT look like:

Reinforcing bars must be carefully and accurately placed to conform to the requirements of engineering. On this pool sealed engineered drawings called for a minimum 4" gunite shell with rebar enforcing placed in the center of the shell wall. These pictures were taken after a weaper was ground out and the area inspected. The high volume contractor was notified by his Project Manager who then refused to correct the problem. His reasoning was it would involve considerable time and expense to the repair. He simply ordered the structural rebar to be cut out and filled with hydraulic cement. It should be noted this particular corner of the swimming pool was at the pool spa joint, a critical area of stress. The concrete thickness from rebar to the back of the shell measured only 2.5 inches with voids less than 1 inch. This home owner unknowingly accepted a pool with a shell of 2.5 inches and considerable structural rebar removed. How did this happen? One word...volume. This contractor boasts of building over 150 pools a year. Without the ability to provide direct supervision of each phase of the pool he must rely on subcontractors to insure a thorough job is completed. Another great reason to avoid high volume production builders.....unless of course future structural failures are acceptable to you.