Alkalinity Calculator

Total alkalinity is a measure of your water's ability to resist pH swings — keeping it in the right range protects your pool equipment and makes chlorine work effectively. Select your Calculation Type (pool/spa or aquarium), enter your pool volume, current total alkalinity, and desired total alkalinity, then choose your sanitizer type and alkalinity increaser to get the exact amount of chemical needed in pounds. Secondary outputs include your calculated pool volume, recommended alkalinity range, and the total alkalinity increase required.

gallons
feet
feet
feet
feet
feet
ppm
ppm

Results

Alkalinity Increaser Needed

--

Calculated Pool Volume

--

Recommended Minimum

--

Recommended Maximum

--

Alkalinity Increase

--

More Chemistry Tools

Frequently Asked Questions

What is the ideal alkalinity range for pools?

The recommended total alkalinity range is 60-180 ppm. For pools using calcium hypochlorite, sodium hypochlorite, or lithium hypochlorite, aim for 80-100 ppm. For pools using sodium dichlor, trichlor, chlorine gas, or bromine, target 100-120 ppm.

How much alkalinity increaser should I add at once?

Do not add all the calculated amount at once. This can cause extreme changes in water chemistry. Add the chemical gradually over several days, testing the water regularly and adjusting as needed.

What happens if my pool alkalinity is too low?

Low alkalinity can cause pH to fluctuate rapidly, leading to corrosion of pool equipment, etching of plaster surfaces, and eye/skin irritation. It also makes pH difficult to maintain.

Can I use baking soda to raise alkalinity?

Yes, sodium bicarbonate (baking soda) is commonly used to raise total alkalinity. Use pure baking soda or commercial alkalinity increasers, which are essentially the same product.

How do I calculate my pool volume if I don't know it?

For rectangular pools: Length × Width × Average Depth × 7.5. For circular pools: Diameter × Diameter × Average Depth × 5.9. For oval pools: Length × Width × Average Depth × 6.7.

Why does sanitizer type affect alkalinity recommendations?

Different sanitizers have varying effects on pH stability. Stabilized chlorines (trichlor, dichlor) are acidic and require higher alkalinity levels to maintain proper pH buffering capacity.

How often should I test my pool's alkalinity?

Test total alkalinity at least once per week, or more frequently if you're having pH stability issues. Always test after adding chemicals or after heavy pool usage.

What's the maximum safe daily increase for alkalinity?

For aquariums, limit increases to less than 1.4 dKH per day to prevent stress. For pools, gradual increases over 2-3 days are recommended rather than large single doses.