Hydraulic Design - Swimming Pools

Whether your pool is a backyard swimming pool, or a vanishing edge, infinity edge, perimeter overflow, negative edge or slot edge - proper hydraulic design principals must be followed.

Too Little - Too Long

The swimming pool industry as a whole has been flying by the seat of their pants for decades.  Salesmen have been specifying pipe and pump sizes using a grossly incorrect rule of thumb - pump horsepower should match pipe diameter.

For example this incorrect theory would use a 2 inch pipe on a 2 horsepower pump.  

This theory results in line velocities that are unsafe, waste energy, create pump noise and result in premature system wear.

Proper Hydraulic Design

Properly designed hydraulic systems should have their pumps selected as the very last item - not the first.

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• Lengths of pipe and fittings need to be summarized and their restrictions calculated.  
• The turnover and flowrate goals must be estimated.  
• Appropriate filter sizing must be selected.  Approximate pipe sizes are selected to maintain flowrates within safe specifications.
• From those estimates and calculations, the total dynamic head (TDH) of the system and the line velocities are calculated.
• If the line velocities or TDH are too high, then minor changes to the assumptions are made (e.g. adjust pipe sizes) and everything is recalculated.
• This process continues until everything is within the proper specifications.
• Then the suction inlets (drains and covers) are selected.
• The suction inlets might need to be divided multiple times to reduce the velocity and flowrates at the inlets.

While hydraulic design is an exact science, the process must start with some basic assumptions.

Properly designed swimming pool hydraulics will result in a quiet filtration system and maximize your energy savings.

Paolo Benedetti - Artist, Aquatic Consultant, Watershape Designer, Expert Witness. 

 

©Aquatic Technology Pool and Spa - 2014

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