Domakihub How to Balance Pool Alkalinity and Keep Water Clear
The simple, chemical-accurate method for getting your pool's total alkalinity into the right range.
Reviewed by Domakihub pool pros · 2026-06-23 · 5 min read
Total alkalinity acts as a buffer for your pool's pH — when it drifts out of range, pH swings become erratic, chlorine loses effectiveness, and swimmers notice irritated eyes or cloudy water. The Swim University video above walks through the chemistry visually; this guide gives you the exact step-by-step process you can follow with any test kit, whether you manage a private pool in Mykonos, a holiday villa in Crete, or a hotel in Athens. Greece's warm summers and high bather loads make alkalinity drift faster than in cooler climates, so testing weekly is worth the two minutes it takes.
Why Alkalinity Matters More Than You Think
Total alkalinity (TA) measures the concentration of carbonate and bicarbonate ions in your water, expressed in parts per million (ppm). Its main job is to resist sudden pH swings — a quality chemists call buffering capacity. When TA is too low, pH bounces all over the place every time someone adds chemicals or rain dilutes the water. When TA is too high, pH locks stubbornly high and no amount of acid seems to bring it down.
The ideal range for most outdoor pools is 80–120 ppm, though pools that use a salt-chlorine generator do best at the lower end (80–100 ppm) to slow scale build-up on the cell plates.
Common Causes of Alkalinity Imbalance in Greek Pools
Heavy summer rain, large bather loads, and the evaporation-and-top-up cycle that is normal in a Mediterranean climate all work to pull TA downward over time. Tap water in many Greek municipalities carries its own alkalinity level — sometimes quite high — which can push TA up when you refill after backwashing. Shocking the pool with high doses of unstabilised chlorine can also drive alkalinity in either direction depending on the product used.
Knowing which direction your alkalinity tends to drift lets you plan: most villa pools that are topped up frequently from municipal supply tend to read high, while pools that receive a lot of rain or use well water often read low.
How to Balance Pool Alkalinity: 5 Steps
- 1
Test the current total alkalinity
Use a reliable test kit — either liquid reagent drops or a digital photometer — to measure your pool's TA in ppm. Dip the sample tube at elbow depth away from the return jets for an accurate mid-pool reading. Write down the result alongside your pH reading, because the two are adjusted together in a specific order.
- 2
Raise low alkalinity with sodium bicarbonate
If your TA reads below 80 ppm, add sodium bicarbonate (baking soda, sold as 'Alkalinity Up' at pool shops). Use the rule of thumb that roughly 1.4 kg of sodium bicarbonate per 50,000 litres raises TA by about 10 ppm. Pre-dissolve the powder in a bucket of pool water, then pour it in front of a return jet with the pump running. Wait at least 6 hours before retesting — do not add more until the water has fully circulated.
- 3
Lower high alkalinity with muriatic acid
If your TA reads above 120 ppm, use muriatic acid (hydrochloric acid, sold as 'pH Down' or 'Minus' at pool shops). Always add acid to water, never the reverse. With the pump off, pour the measured dose in a slow arc across the deep end. Run the pump for 30 minutes, then turn it off and let the water rest for 8–12 hours. Retest before adding any further acid. Tip: aeration — running a fountain, waterfall, or just letting the return jets break the surface — helps outgas CO₂ after acid treatment and fine-tunes pH back upward without raising TA further.
- 4
Recheck pH and adjust if needed
After correcting TA, check your pH. The target is 7.2–7.6. Because sodium bicarbonate raises both TA and pH slightly, and muriatic acid lowers both, you may need a minor pH correction at this point. Use pH Minus (sodium bisulphate or diluted muriatic acid) to nudge pH down, or pH Plus (sodium carbonate) to bring it up. Make small adjustments — no more than 0.2 pH units at a time — and re-circulate for two hours before retesting.
- 5
Re-test after 24 hours and log the result
Return the next day and test again. Alkalinity sometimes takes a full circulation cycle to fully stabilise. Record the date, TA reading, pH, and what chemicals you added. This log becomes invaluable for seasonal planning — especially if you manage multiple properties or hand the pool over to a caretaker. In peak season (July–August) in Greece, weekly testing is the minimum; bi-weekly is safer for high-bather-load hotel pools.
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FAQ
- Should I adjust alkalinity or pH first?
- Always adjust total alkalinity first. Because TA acts as a buffer for pH, correcting alkalinity first makes your subsequent pH adjustment more predictable and stable. Trying to fix pH in a pool with wild TA swings often leads to a frustrating see-saw cycle.
- How quickly can I add chemicals to fix alkalinity?
- Do not rush. Add one dose, run the pump for the recommended time, then wait at least 6–8 hours before retesting and adding more. Over-dosing is both expensive and counterproductive — adding too much sodium bicarbonate can push TA and pH sky-high, requiring an acid correction immediately after.
- Can high alkalinity damage a pool?
- Yes. Sustained high TA (above 150 ppm) creates conditions where calcium scale builds up on surfaces, waterline tiles, and equipment. It also makes the water look permanently hazy even after shocking, and it forces your pH high enough that chlorine becomes much less effective at sanitising the water.