Yes, granular pool shock should be dissolved in water before adding to prevent bleaching and ensure even distribution. Liquid shock can be added directly to the pool while walking around the perimeter.
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Yes, granular pool shock must be dissolved in water before adding to your pool. Liquid shock (sodium hypochlorite) can be added directly. Pre-dissolving granular shock prevents liner damage, surface bleaching, and ensures even chemical distribution throughout your pool water.
Granular shock products like calcium hypochlorite contain concentrated chlorine that creates localized "hot spots" when added directly to pool water. These concentrated areas can:
The dissolution process ensures your shock treatment works effectively while protecting your pool investment.
This is the most common granular shock, typically 65-70% available chlorine. Always dissolve cal-hypo shock completely before adding. Use a 5-gallon bucket filled with pool water, add shock slowly while stirring, then pour the dissolved solution around the pool perimeter with the pump running.
Dichlor shock dissolves more easily than cal-hypo but should still be pre-dissolved for best results. This stabilized shock adds cyanuric acid (CYA) to your pool, so monitor CYA levels carefully. Target CYA levels are 30-50 ppm for regular chlorine pools and 70-80 ppm for salt water generators.
Liquid chlorine (typically 10-12.5% sodium hypochlorite) can be added directly to your pool. Walk around the deep end perimeter while pouring to ensure even distribution. This is actually the preferred shock method for SLAM (Shock Level And Maintain) treatments when dealing with algae problems.
This oxygen-based shock should be dissolved before adding, though it's less likely to cause surface damage than chlorine-based shocks. Use it when you need to oxidize contaminants without raising chlorine levels.
Never mix different types of pool chemicals. Clean your dissolution bucket thoroughly between uses. Wear safety goggles and gloves when handling granular shock. Store chemicals in a cool, dry place away from other pool chemicals.
When dissolving cal-hypo shock, the solution may become warm - this is normal. However, if it becomes hot or starts smoking, you've added too much too quickly. Dilute immediately with more pool water.
For routine weekly shocking, add 1 pound of granular shock per 10,000 gallons of pool water. For green pool treatment using the SLAM method, maintain free chlorine at shock level (determined by your CYA level) until you pass the overnight chlorine loss test and achieve clear water.
When using liquid chlorine for SLAM treatments, you'll typically need 1-3 gallons per day depending on your pool size and algae severity. Test chlorine levels every few hours initially, then twice daily as levels stabilize.
The only time you don't need to dissolve shock is when using liquid sodium hypochlorite. Quality liquid chlorine from pool stores or even unscented household bleach (5.25% sodium hypochlorite) can be added directly to the pool.
Some pool owners prefer liquid chlorine specifically because it eliminates the dissolution step while providing more consistent results than granular products.
Wait at least 30 minutes after adding dissolved shock before testing chlorine levels. For accurate readings, test when the pump has been running to ensure proper mixing. Your target free chlorine level depends on your stabilizer (CYA) level - higher CYA requires higher chlorine levels for effective sanitization.
Retest chlorine levels the following morning. If you lose more than 1 ppm overnight, continue the SLAM process until you achieve stable chlorine levels with clear, algae-free water.
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