Question 1

How much chlorine does it take to raise free chlorine 1 ppm?

Accepted Answer

In 10,000 gallons, about 10 fl oz of 12.5% liquid chlorine, or about 2 oz of 65% cal-hypo, raises free chlorine roughly 1 ppm. The calculator scales this to your exact volume and target, and shows the dose for every product form so you can use whatever is on the truck.

Question 2

How much acid do I add to lower pH?

Accepted Answer

It depends on volume and how high your alkalinity is, because alkalinity buffers the change. As a rough guide, dropping pH from 7.8 to 7.5 in 10,000 gallons at 100 ppm alkalinity takes around 8 to 10 fl oz of 31.45% muriatic acid. Enter your numbers for the exact amount. Lowering pH also lowers alkalinity.

Question 3

What should my LSI be?

Accepted Answer

Aim for an LSI between -0.3 and +0.3, with 0.0 being ideal. Below -0.3 the water is corrosive and pulls minerals out of plaster and metal. Above +0.3 it scales and deposits on surfaces, plumbing, and salt cells. Salt pools use a slightly different constant (12.2 instead of 12.1) because of higher total dissolved solids.

Question 4

How do I lower cyanuric acid (CYA)?

Accepted Answer

There is no chemical that removes CYA. The only way to lower it is to drain part of the water and refill with fresh. The calculator tells you what percentage of the water to replace to hit your target. The same is true for calcium hardness that is too high.

Question 5

Does dichlor or trichlor raise CYA?

Accepted Answer

Yes. Every 1 ppm of free chlorine from dichlor adds about 0.9 ppm CYA, and from trichlor about 0.6 ppm CYA. Over a season that adds up and can lock your chlorine. The calculator flags this on each product so you can watch your stabilizer level.

Question 6

Is this calculator accurate enough for professional use?

Accepted Answer

The dosing uses standard industry constants from the Pool and Hot Tub Alliance handbook and is tested against known benchmarks. That said, water is not a lab. Treat the numbers as a strong starting point, add in smaller steps, and always retest before adding more.

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Step 1: Pool volume

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