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Pool & Recreation

Water volume, chemical dosing and room sizing for pools and games rooms.

Volume first, chemistry second

Every pool chemical dose depends on the water volume, so that is the figure to establish first and record somewhere permanent. Get it wrong once and every dose afterwards is wrong by the same proportion, which is why the volume calculator handles sloping floors as an average depth rather than assuming a flat bottom.

Dosing is a ratio by weight, not by volume, which is why parts per million convert through the weight of the water rather than its gallons. It is also why product strength matters so much: a pound of 65% cal-hypo delivers more than five times the chlorine of a pound of 12.5% liquid, and no dose calculated for one is safe to use with the other.

Working with pool chemicals

  • Record your pool volume once and keep it.
  • Read the available chlorine off the label, every time.
  • Add about three quarters of a dose, then test again.
  • Shock in the evening — sunlight destroys free chlorine.

Questions

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Because cell output and cell life both depend on it. Manufacturers specify somewhere between roughly 2,700 and 3,400 ppm and the unit will alarm or throttle outside its own range. There is no universal figure, so the manual governs rather than any calculator default.

No, and this is the most expensive assumption in pool chemistry. Cal-hypo is around 65% available chlorine, dichlor 56%, liquid only 12.5%. Matching by weight rather than by strength either wastes product or leaves the pool badly under-dosed.

The only remedy is dilution — drain part of the pool and refill. Nothing removes salt chemically, and salt is not consumed by the generator, so it only leaves through splash out, backwashing and overflow. Under-dose deliberately and top up after testing.

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