Maintaining a swimming pool requires precision. Over-treating your water can lead to skin irritation and equipment damage, while under-treating can allow algae and bacteria to thrive. This calculator helps you determine the exact weight or volume of chemicals required based on your specific pool volume.
Understanding the Math
Pool chemical dosages are calculated based on the 10,000-gallon standard. For example:
Free Chlorine: To raise chlorine by 1 ppm in 10,000 gallons, you typically need 2 oz of liquid bleach (10%) or 1.5 oz of Calcium Hypochlorite (65%).
Total Alkalinity: To raise TA by 10 ppm in 10,000 gallons, you need 1.5 lbs of Sodium Bicarbonate.
Calcium Hardness: To raise hardness by 10 ppm in 10,000 gallons, you need roughly 1.2 lbs of Calcium Chloride.
Recommended Chemical Ranges
Chemical
Ideal Range
Free Chlorine
1.0 – 3.0 ppm
pH Level
7.4 – 7.6
Total Alkalinity
80 – 120 ppm
Calcium Hardness
200 – 400 ppm
Cyanuric Acid
30 – 50 ppm
Pro Maintenance Tips
1. Always Pre-dissolve: When adding dry chemicals like Calcium Chloride or Sodium Bicarbonate, dissolve them in a bucket of pool water first to prevent liner staining.
2. Circulation is Key: Ensure your pump is running when adding chemicals and let it run for at least 4-6 hours before re-testing.
3. The Order Matters: Always balance Total Alkalinity before adjusting pH, as alkalinity acts as a buffer for pH levels.
function calculatePoolChemicals() {
var volume = parseFloat(document.getElementById('poolVolume').value);
var current = parseFloat(document.getElementById('currentLevel').value);
var target = parseFloat(document.getElementById('targetLevel').value);
var type = document.getElementById('chemicalType').value;
var resultDisplay = document.getElementById('poolResultDisplay');
var resultBox = document.getElementById('poolResultBox');
var resultNote = document.getElementById('poolResultNote');
if (isNaN(volume) || isNaN(current) || isNaN(target) || volume <= 0) {
alert('Please enter valid numeric values for volume and chemical levels.');
return;
}
if (target <= current) {
alert('Target level must be higher than the current level.');
return;
}
var difference = target – current;
var amount = 0;
var unit = "";
var chemicalName = "";
// Calculation Logic
if (type === "chlorine") {
// Formula: 1.5 oz of 65% Cal-Hypo increases 10,000 gal by 1 ppm
amount = (difference) * (volume / 10000) * 1.5;
unit = "oz";
chemicalName = "Calcium Hypochlorite (65%)";
resultNote.innerHTML = "Note: Add the chlorine in the evening for best results to avoid UV degradation.";
} else if (type === "alkalinity") {
// Formula: 1.5 lbs Sodium Bicarb increases 10,000 gal by 10 ppm
amount = (difference / 10) * (volume / 10000) * 1.5;
unit = "lbs";
chemicalName = "Sodium Bicarbonate (Baking Soda)";
resultNote.innerHTML = "Note: High alkalinity can cause cloudy water and scale formation.";
} else if (type === "hardness") {
// Formula: 1.2 lbs Calcium Chloride increases 10,000 gal by 10 ppm
amount = (difference / 10) * (volume / 10000) * 1.2;
unit = "lbs";
chemicalName = "Calcium Chloride";
resultNote.innerHTML = "Note: Low calcium levels can lead to the erosion of pool surfaces and grout.";
} else if (type === "cya") {
// Formula: 0.8 lbs Cyanuric Acid increases 10,000 gal by 10 ppm
amount = (difference / 10) * (volume / 10000) * 0.8;
unit = "lbs";
chemicalName = "Cyanuric Acid (Stabilizer)";
resultNote.innerHTML = "Note: Cyanuric acid protects chlorine from the sun, but levels above 100 ppm can be problematic.";
}
resultDisplay.innerHTML = amount.toFixed(2) + " " + unit + " of " + chemicalName;
resultBox.style.display = "block";
}