Troubleshooting Guide
Your pool looks like milk and you want to swim this weekend. Here's how to diagnose the problem and fix it fast, with exact chemical amounts.
Before you add anything to your pool, test the water. You can't fix what you can't measure. Grab your test kit or strips and check free chlorine, pH, and total alkalinity at minimum. The results will point you to the cause.
Don't have a test kit?
Basic test strips from any hardware store work fine. Taylor K-2006 is the gold standard if you want accuracy. Don't skip this step. Adding chemicals blindly usually makes things worse.
How to tell: Free chlorine is below 1 ppm. Water may have a slight green tint along with the cloudiness.
Why it happens: Heavy use, rain, hot weather, or forgetting to add chlorine. UV rays destroy chlorine fast without CYA protection.
The fix: Shock the pool. Add calcium hypochlorite or liquid chlorine to raise free chlorine to 10 ppm (shock level). Run the pump 24 hours. The cloudiness should clear within 12 to 48 hours.
How much: About 1 lb of cal-hypo shock per 10,000 gallons to raise FC by about 5 ppm. For liquid chlorine, about 1 gallon per 10,000 gallons raises FC by about 1 ppm.
How to tell: pH reads above 7.8. Chlorine levels might look fine, but the water is still hazy.
Why it happens: High pH makes chlorine less effective (even if the reading looks good), and causes calcium to precipitate out of the water, creating that milky look.
The fix: Lower pH with muriatic acid or dry acid (sodium bisulfate). Target 7.4.
How much: About 1 quart of muriatic acid per 10,000 gallons lowers pH by about 0.2. Add slowly with the pump running, away from the skimmer.
How to tell: Total alkalinity is above 120 ppm. pH is probably high too.
Why it happens: Over-adding baking soda, certain fill water sources, or buildup from chemicals over time.
The fix: Lower alkalinity with muriatic acid. This will also bring pH down.
How much: About 1.6 quarts of muriatic acid per 10,000 gallons lowers alkalinity by 10 ppm. Add in small doses, retest after 4 to 6 hours.
How to tell: Calcium hardness reads above 400 ppm. You might see white scale on the waterline tile too.
Why it happens: Hard fill water, over-addition of calcium chloride, or calcium leaching from plaster surfaces.
The fix: There's no chemical that removes calcium from water. You need to partially drain the pool and refill with fresh water to dilute it.
How much to drain: If calcium is at 600 ppm and your target is 300 ppm, drain about half the water. Test your fill water's calcium level first to calculate accurately.
How to tell: Your chemistry looks fine, but the water is still cloudy. Check when you last cleaned your filter.
Why it happens: A dirty filter can't catch the tiny particles making your water cloudy. Running your pump too few hours per day also contributes.
The fix: Clean or backwash your filter. Run the pump at least 8 to 12 hours per day until the water clears. If the filter is old or damaged, it may be time for a replacement.
Pro tip: After shocking, your filter is doing heavy lifting. Clean it again 24 to 48 hours after a shock treatment to keep it working efficiently.
Test your water at least once a week (twice in summer)
Run your pump 8 to 12 hours daily during swim season
Keep free chlorine between 1 and 4 ppm at all times
Maintain pH between 7.2 and 7.6
Clean or backwash your filter monthly
Shock after heavy use, rain, or when water looks off
Pool Clarity takes your test results and your exact pool size and tells you precisely what to add, how much, and in what order. No guessing, no trips to the pool store.
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