Water circulation

  • Basically a pool is a water storage tank that is also used for swimming.
  • The water is circulated via a system of pipes and into a water filtration plant.

Skimmer boxes

  • A skimmer box is a pre cast plastic bucket like weir that is set into the pool wall during concreting stage.
  • The skimmer box has a window opening facing into the pool and usually a front weir flap.
  • The skimmer is set at a height that enables the water level to be approximately half way up the window.
  • Water flows into the skimmer box and then travels in the suction line away to the filter.
  • The skimmer box is designed to draw water from the surface and collect floating dust and leaves etc.
  • Inside the skimmer box is a leaf trap basket to catch leaves and other floating items.
  • There is a safety lid which opens from the top of the skimmer to enable access to the basket.
  • Modern skimmers in concrete pools are very safe for children and the lid can be locked down if required.
  • Skimmer lids are available in a range of colours to match paving or decking that forms the pool surrounds.
  • Some larger home pools may require two or more skimmer boxes based on a suggested formula of one skimmer for every 30m2 of pool surface area.
  • For pool locations with lots of trees we advise extra skimmer boxes and hence more leaf traps.
  • One of the regular pool jobs is to clean out the basket.
  • You can train your kids to do that.

Pipe sizes

  • Water resistance in pipes reduces as the pipe diameter increases.
  • If the water resistance is too high you will be wasting energy and increasing your power bill.
  • Most household pools have a 50mm suction line from the skimmer boxes to the pump.
  • Also extra bends in the pipes add to the resistance so a short straight suction line pipe is the best for water flow.
  • The circulation pump is located in the pipework before the filter.
  • The water is pushed into filter by the pump.
  • The pump has a hair and lint pot with another basket to catch smaller rubbish before it gets to the filter.
  • After passing through the filter and sterilization system, such as a salt chlorinator, the water returns to the pool in 40mm or 50mm pipework.
  • The size of the pipe depends on the filtration pump size.
  • The pump is selected by the pool builder based on the water flow that it creates and the time to circulate all of the pool water.
  • In my experience we try to circulate the entire pool in a 6 hour period or less.

For the academics: a simple formula is

  • (Pool volume in litres) divided by 4 hours divided by 60 minutes = flow rate /minute.
  • We expect a Zodiac 1.0HP pump to circulate 300 litres/ minute.
  • Putting a bigger pump on the system will not flow any better without also upgrading all of the pipework diameter.

Adjustable pool return eyeballs

  • Your pool designer will locate the water returns positions hopefully towards the skimmer boxes to assist with surface skimming.
  • The number of return eyeballs is a function of pool shape and even prevailing winds.
  • The eyeballs are just under the water level and the direction can be adjusted from inside the pool.
  • Most eyeballs are white plastic however for people who like a bit of BLING, stainless steel eyeballs are available at an extra cost.

Heater pipes just for the heater

  • I believe the most efficient heating method is to have the heater and the filter system on separate plumbing lines.
  • The pump, filter and chlorinator sterilize the water and are usually activated during pre-set times such as the morning and evening.
  • The heater however with a timer and thermostatic control operates when the temperature switch activates the heater. The running times obviously can be different.

Heaters

  • Pool water is colder at the deepest section
  • Therefore heater pipe suctions are placed lower in the pool wall than the surface eyeball returns.
  • The cold water is then circulated to the heater and then also returns to the lower section of the pool.
  • Science says hot water then rises to the top and hopefully provides an evenly heated pool.
  • Heater pipes installed in the pool shell at concrete stage can enable future heater installation without having to dig up the pipes.
  • Heater pipes safety suctions have to be greater than 1.0 m apart so people cannot get caught in the suctions.
  • Heater pipes usually have two suctions and two returns so you will have two more eyeballs and two safety suction covers.

Standard equipment location

  • The pumps and filters are best located more than 3.5 m from the pool and hopefully less than 10m.
  • Longer suction lines may require larger diameter pipes and more powerful pumps and extra costs.
  • Filter location is one of the first items covered in our initial design interview.