Pool Chemical Adjustment Calculator
Use this calculator to determine the approximate amount of chemicals needed to adjust your pool's Free Chlorine, pH, and Total Alkalinity levels. Always retest your water after adding chemicals and follow product instructions.
Pool Information
Free Chlorine Adjustment
Liquid Chlorine (10% Sodium Hypochlorite) Liquid Chlorine (12.5% Sodium Hypochlorite) Granular Cal-Hypo (68% Calcium Hypochlorite) Granular Dichlor (99% Sodium Dichlor)
pH Adjustment
pH Increaser (Soda Ash) pH Decreaser (Dry Acid – Sodium Bisulfate)
Total Alkalinity Adjustment
Recommended Chemical Adjustments:
"; var isValid = true; // Input validation if (isNaN(poolVolumeGallons) || poolVolumeGallons <= 0) { output += "Please enter a valid Pool Volume in gallons."; isValid = false; } if (isNaN(currentFreeChlorine) || currentFreeChlorine < 0 || isNaN(desiredFreeChlorine) || desiredFreeChlorine < 0) { output += "Please enter valid Free Chlorine levels (ppm)."; isValid = false; } if (isNaN(currentpH) || currentpH 9 || isNaN(desiredpH) || desiredpH 9) { output += "Please enter valid pH levels (between 6.0 and 9.0)."; isValid = false; } if (isNaN(currentAlkalinity) || currentAlkalinity < 0 || isNaN(desiredAlkalinity) || desiredAlkalinity currentFreeChlorine) { var fcIncreaseNeeded = desiredFreeChlorine – currentFreeChlorine; var chlorineAmount = 0; var chlorineUnit = ""; var chlorineProductDisplayName = ""; // Constants for 1 ppm FC increase in 10,000 gallons // Liquid: gallons, Granular: ounces var liquid10Factor = 0.10; // gallons var liquid12_5Factor = 0.08; // gallons var calHypo68Factor = 0.13; // ounces var dichlor99Factor = 0.16; // ounces switch (chlorineProductType) { case 'liquid10': chlorineAmount = (poolVolumeGallons / 10000) * fcIncreaseNeeded * liquid10Factor; if (chlorineAmount < 1) { // If less than 1 gallon, convert to fl oz chlorineAmount *= 128; // 1 gallon = 128 fl oz chlorineUnit = "fluid ounces (fl oz)"; } else { chlorineUnit = "gallons"; } chlorineProductDisplayName = "Liquid Chlorine (10%)"; break; case 'liquid12_5': chlorineAmount = (poolVolumeGallons / 10000) * fcIncreaseNeeded * liquid12_5Factor; if (chlorineAmount < 1) { // If less than 1 gallon, convert to fl oz chlorineAmount *= 128; // 1 gallon = 128 fl oz chlorineUnit = "fluid ounces (fl oz)"; } else { chlorineUnit = "gallons"; } chlorineProductDisplayName = "Liquid Chlorine (12.5%)"; break; case 'calhypo68': chlorineAmount = (poolVolumeGallons / 10000) * fcIncreaseNeeded * calHypo68Factor; chlorineUnit = "ounces (oz)"; chlorineProductDisplayName = "Granular Cal-Hypo (68%)"; break; case 'dichlor99': chlorineAmount = (poolVolumeGallons / 10000) * fcIncreaseNeeded * dichlor99Factor; chlorineUnit = "ounces (oz)"; chlorineProductDisplayName = "Granular Dichlor (99%)"; break; } output += "To raise Free Chlorine from " + currentFreeChlorine + " ppm to " + desiredFreeChlorine + " ppm, add approximately " + chlorineAmount.toFixed(2) + " " + chlorineUnit + " of " + chlorineProductDisplayName + "."; } else if (desiredFreeChlorine currentpH) { var pHIncreaseNeeded = desiredpH – currentpH; var sodaAshAmount = 0; // Constant for 0.1 pH increase in 10,000 gallons using Soda Ash (ounces) var sodaAshFactor = 6; // ounces sodaAshAmount = (poolVolumeGallons / 10000) * (pHIncreaseNeeded / 0.1) * sodaAshFactor; output += "To raise pH from " + currentpH + " to " + desiredpH + ", add approximately " + sodaAshAmount.toFixed(2) + " ounces (oz) of pH Increaser (Soda Ash). Do not raise pH by more than 0.2-0.3 in a single application."; } else if (desiredpH < currentpH) { var pHDecreaseNeeded = currentpH – desiredpH; var dryAcidAmount = 0; // Constant for 0.1 pH decrease in 10,000 gallons using Dry Acid (ounces) var dryAcidFactor = 8; // ounces dryAcidAmount = (poolVolumeGallons / 10000) * (pHDecreaseNeeded / 0.1) * dryAcidFactor; output += "To lower pH from " + currentpH + " to " + desiredpH + ", add approximately " + dryAcidAmount.toFixed(2) + " ounces (oz) of pH Decreaser (Dry Acid). Do not lower pH by more than 0.2-0.3 in a single application."; } else { output += "pH is at the desired level (" + currentpH + "). No adjustment needed."; } // — Total Alkalinity Calculation — if (desiredAlkalinity > currentAlkalinity) { var taIncreaseNeeded = desiredAlkalinity – currentAlkalinity; var bicarbAmount = 0; // Constant for 10 ppm TA increase in 10,000 gallons using Sodium Bicarbonate (pounds) var bicarbFactor = 1.5; // pounds bicarbAmount = (poolVolumeGallons / 10000) * (taIncreaseNeeded / 10) * bicarbFactor; output += "To raise Total Alkalinity from " + currentAlkalinity + " ppm to " + desiredAlkalinity + " ppm, add approximately " + bicarbAmount.toFixed(2) + " pounds (lbs) of Alkalinity Increaser (Sodium Bicarbonate)."; } else if (desiredAlkalinity < currentAlkalinity) { output += "Total Alkalinity is currently " + currentAlkalinity + " ppm. To lower TA, you typically need to lower pH significantly (e.g., to 7.0-7.2) and then aerate the water. Consult a pool professional for significant TA reduction."; } else { output += "Total Alkalinity is at the desired level (" + currentAlkalinity + " ppm). No adjustment needed."; } resultDiv.innerHTML = output; } .pool-chemical-calculator { font-family: 'Arial', sans-serif; background-color: #f9f9f9; padding: 20px; border-radius: 8px; box-shadow: 0 2px 4px rgba(0, 0, 0, 0.1); max-width: 700px; margin: 20px auto; border: 1px solid #ddd; } .pool-chemical-calculator h2, .pool-chemical-calculator h3 { color: #0056b3; text-align: center; margin-bottom: 15px; } .pool-chemical-calculator p { line-height: 1.6; margin-bottom: 10px; } .calculator-form label { display: block; margin-bottom: 5px; font-weight: bold; color: #333; } .calculator-form input[type="number"], .calculator-form select { width: calc(100% – 22px); padding: 10px; margin-bottom: 15px; border: 1px solid #ccc; border-radius: 4px; box-sizing: border-box; } .calculator-form button { background-color: #007bff; color: white; padding: 12px 20px; border: none; border-radius: 4px; cursor: pointer; font-size: 16px; width: 100%; transition: background-color 0.3s ease; } .calculator-form button:hover { background-color: #0056b3; } .calculator-result { margin-top: 20px; padding: 15px; background-color: #e9f7ef; border: 1px solid #d4edda; border-radius: 5px; color: #155724; } .calculator-result h3 { color: #155724; margin-top: 0; } .calculator-result p { margin-bottom: 8px; } .calculator-result p strong { color: #0056b3; }Understanding Your Pool's Chemical Balance
Maintaining proper chemical balance in your swimming pool is crucial for several reasons: it ensures swimmer comfort and safety, protects your pool equipment from damage, and keeps the water sparkling clean and clear. Neglecting chemical balance can lead to cloudy water, algae growth, skin and eye irritation, and even corrosion of pool surfaces and components.
Key Pool Chemical Parameters:
- Free Chlorine (FC): This is the active sanitizer in your pool, responsible for killing bacteria, viruses, and algae. The ideal range for Free Chlorine is typically 1-3 ppm (parts per million), though some experts recommend 2-4 ppm. Maintaining adequate FC levels is paramount for a healthy pool.
- pH: pH measures how acidic or basic your pool water is. The ideal pH range is 7.4-7.6, closely matching the pH of human eyes and mucous membranes. A low pH (acidic) can cause eye irritation, corrosion of equipment, and rapid dissipation of chlorine. A high pH (basic) can lead to cloudy water, scale formation, and reduced chlorine effectiveness.
- Total Alkalinity (TA): TA acts as a buffer for your pH, preventing drastic fluctuations. The ideal range for Total Alkalinity is 80-120 ppm. Low TA can cause pH to "bounce" erratically, while high TA can make it difficult to adjust pH and contribute to cloudy water and scaling.
- Calcium Hardness (CH): This measures the amount of dissolved calcium in your water. The ideal range is 150-250 ppm (or up to 400 ppm for plaster pools). Low CH can cause corrosive water, leading to etching of plaster and damage to equipment. High CH can lead to scale formation on surfaces and equipment. (Note: This calculator focuses on FC, pH, and TA, but CH is also vital.)
- Cyanuric Acid (CYA): Also known as conditioner or stabilizer, CYA protects chlorine from degradation by UV rays. The ideal range is 30-50 ppm for outdoor pools. Too little CYA means chlorine dissipates quickly; too much can "lock up" chlorine, making it ineffective.
How to Use the Calculator:
To get accurate recommendations, you'll need to perform a recent water test using a reliable test kit or strips. Input your pool's total volume in gallons, along with the current readings for Free Chlorine, pH, and Total Alkalinity. Then, enter your desired target levels for each parameter. The calculator will provide an estimate of the chemical amounts needed.
Important Considerations:
- Add Chemicals Slowly: Never dump large quantities of chemicals directly into one spot. Always dilute granular chemicals in a bucket of pool water before adding, and distribute liquid chemicals evenly around the pool, away from skimmers.
- Retest After Adjustment: Wait several hours (or as recommended by the chemical manufacturer) and retest your water before adding more chemicals. It's often better to make small adjustments over time than to overshoot.
- Never Mix Chemicals: This is extremely dangerous and can cause violent reactions, explosions, or toxic gas release. Always add chemicals separately and rinse buckets thoroughly between uses.
- Safety First: Always wear appropriate safety gear (gloves, eye protection) when handling pool chemicals. Store chemicals in a cool, dry, well-ventilated area, out of reach of children and pets.
- Order of Adjustment: Generally, it's recommended to adjust Total Alkalinity first, then pH, and finally Free Chlorine. TA acts as a buffer for pH, so getting it right first makes pH adjustments easier.
This calculator provides estimates based on common industry guidelines. Actual results may vary depending on water temperature, existing water chemistry, and specific product formulations. For complex issues or persistent problems, consult a certified pool professional.