✦ Pool Chemistry
Determine the exact amount of pool shock required to break down combined chloramines, clear severe green algae blooms, and sanitize your pool water efficiently based on your Cyanuric Acid (CYA) levels.
Step 1: Why are you shocking the pool?
Raises free chlorine to ~10 ppm for regular sanitation
Step 2: Select Type of Pool Shock
Step 3: Enter Pool Specifications
Guide
Follow these core steps in the evening for the best results, as the sun’s UV rays burn off unstabilized chlorine quickly.
Before adding shock, test your pool water. Ensure your pH is between 7.2 and 7.4 and Total Alkalinity is between 80 and 120 ppm. Shocking is significantly more effective when your water chemistry is properly balanced.
Determine your pool’s total volume and choose your shock type. Use the calculator above to find the exact ounces or liters required based on your current free chlorine level and the reason you are treating the pool.
If you are using liquid shock, you can pour it directly into the pool. If using granular shock like Cal-Hypo, pre-dissolve it in a 5-gallon bucket of pool water first to prevent the concentrated grains from bleaching or damaging your pool liner.
Turn on your pool’s filtration pump to maximum speed. Slowly pour the prepared shock mixture around the deep end and edges of the pool perimeter. Walk around while pouring to ensure uniform distribution and optimal chemical circulation.
Keep your pool filter running continuously for at least 8 to 24 hours after treating. Re-test the water before letting anyone enter; it is safe to swim once your Free Chlorine level drops back down to a safe range between 1 and 4 ppm.
FAQ
Not exactly. Chlorine is a chemical sanitizer that maintains daily cleanliness, while “shock” is a high-intensity chemical treatment method. Most pool shocks are made of concentrated chlorine, but they are designed to drastically raise sanitizer levels all at once to burn off combined chlorine (chloramines) and organic waste.
You should shock your pool at dusk or night. Sunlight’s UV rays burn off unstabilized chlorine in as little as 1 to 2 hours. Shocking after sunset ensures the chemical stays in the water long enough to aggressively eliminate bacteria and algae.
It depends on the type. Calcium Hypochlorite (Cal-Hypo) and Liquid Chlorine have high native pH levels and will temporarily raise your pool’s pH. Dichlor shock is slightly acidic and won’t noticeably increase pH, while Non-Chlorine shock (MPS) is neutral to slightly acidic.
Yes, absolutely. Run your filtration pump on its highest speed setting for at least 8 to 24 hours after adding shock. Continuous circulation is vital to distribute the chemical evenly, prevent concentrated bleaching, and filter out dead algae debris.
It is difficult to “over shock” from a sanitation standpoint, as heavy algae blooms often require a double or triple dose. However, adding too much granular stabilized shock (like Dichlor) can cause dangerous Cyanuric Acid buildup, and adding too much Cal-Hypo can unsafely spike your Calcium Hardness levels over time.
This typically happens for three reasons: your pH is too high (which renders chlorine ineffective), your Cyanuric Acid (stabilizer) is too high causing “chlorine lock,” or you didn’t add enough shock to completely kill off a heavy algae bloom. Test your water balance and re-calculate your required target ppm.
