Maintaining a clean and healthy swimming pool involves several key steps, and one of the most important among them is shocking the pool. Pool shocking helps remove contaminants, bacteria, and chloramines that can cloud the water or make it unsafe for swimming. When you add a shock treatment, a common question arises: should you filter or recirculate the pool water during the process? Understanding how your pool system functions and the role of circulation can make all the difference in maximizing the effectiveness of pool shocking. In this topic, we will explore whether to use the filter or recirculate setting when shocking your pool, and what each option does.
Understanding the Pool Pump and Multiport Valve Settings
The Basics of Pool Circulation
Your pool pump is the heart of your filtration system. It draws water from the pool, passes it through the filter, and returns it back. The multiport valve connected to your pool filter has multiple settings, each designed for specific tasks. When shocking your pool, knowing how to manipulate these settings helps you circulate the chemicals effectively while preventing damage to your filter.
Common Multiport Settings Explained
- Filter Normal operation. Water passes through the filter and is returned to the pool.
- Recirculate Water bypasses the filter and goes directly back into the pool.
- Backwash Reverses water flow through the filter to clean it (for sand or DE filters).
- Rinse Clears out any debris left after backwashing.
- Waste Sends water out of the system, bypassing both filter and return lines.
- Closed Shuts off all flow to and from the filter.
What Does Pool Shocking Do?
Purpose of Shocking
Shocking a pool involves adding a large dose of chlorine or a non-chlorine oxidizer to quickly raise the free chlorine level and destroy organic contaminants, bacteria, and chloramines. This process restores clarity, removes unpleasant odors, and prevents algae growth. Regular shocking is especially necessary after heavy pool usage, rainstorms, or when you notice cloudiness or green water.
Types of Pool Shock
- Calcium Hypochlorite The most common type of chlorine shock.
- Sodium Dichlor Contains stabilizer; better for vinyl liner pools.
- Non-chlorine Shock Potassium monopersulfate; safe for immediate swimming after use.
Should You Filter or Recirculate During Pool Shocking?
When to Use the Filter Setting
In most situations, you should use the filter setting while shocking your pool. This allows the shock to move through the pool’s entire circulation system, and any debris or contaminants that get broken down can be trapped in the filter media. The movement of water helps distribute the shock treatment evenly and quickly. However, make sure your pool filter is clean and operating efficiently before shocking.
When to Use the Recirculate Setting
The recirculate setting should be used in special circumstances. If your filter is dirty, fragile, or you’re using a product that could clog the filter, recirculation is the safer option. Since this setting bypasses the filter entirely, it helps distribute the chemicals without putting strain on the filtration system.
Recirculate is especially useful when:
- Your filter is due for maintenance or cleaning.
- You are using flocculants or other products that might cause clogging.
- You want to prevent fine debris from collecting in the filter during the shock process.
Steps to Shock the Pool with Proper Circulation
1. Test and Balance the Water
Before shocking, test the pool water. Ensure pH is between 7.2 and 7.6. High pH can reduce chlorine effectiveness, while low pH can be corrosive. Adjust alkalinity and other levels as needed.
2. Choose the Right Time
Shock the pool in the evening or at night. Sunlight breaks down chlorine quickly, so nighttime application allows the shock to work more effectively. Turn off any pool heater during this time.
3. Turn On the Pump
Start your pump and set the valve to filter for normal circulation. Let it run continuously for at least 812 hours after adding the shock. This ensures the product is evenly dispersed and can reach all corners of the pool.
4. Add the Shock Product
Pre-dissolve the shock in a bucket of water (if required by the manufacturer), then slowly pour it around the perimeter of the pool. Avoid directly pouring it into the skimmer. Keep the pump running during the process.
5. Monitor the Water
After 1224 hours, test the water again. Free chlorine levels should return to safe levels (13 ppm). If chlorine levels are still high, wait before swimming. You may also clean the filter if it captured any visible debris.
Potential Problems and How to Avoid Them
Cloudy Water After Shocking
Cloudiness can occur due to improper circulation, imbalanced pH, or residue from the shock. If your pool remains cloudy, consider backwashing the filter or adding a clarifier to help bind ptopics for easier filtration.
High Chlorine Levels
After shocking, chlorine levels may remain elevated for a while. This is normal, but don’t allow swimmers until levels drop below 5 ppm. Run the pump continuously and avoid adding more chlorine during this period.
Filter Damage
If you run the filter setting with a clogged or failing filter, it could cause pressure buildup or backflow issues. Always check your filter pressure gauge and clean or replace filter elements as necessary.
Tips for Best Results
- Always pre-dissolve granular shock unless labeled as fast-dissolving.
- Use the recirculate setting for initial mixing if you are unsure about filter conditions.
- Switch back to filter once water has had time to mix thoroughly and shock has begun to work.
- Brush the pool walls and floor to loosen debris before shocking.
- Vacuum the pool after shocking if debris settles to the bottom.
When shocking your pool, the ideal setting depends on your specific pool system and the condition of your filter. For most scenarios, using the filter setting allows for the most effective distribution of pool shock and removal of contaminants. However, the recirculate setting can be helpful when you need to bypass the filter to prevent clogging or when adding chemicals that might interfere with normal filtration. Understanding how to use your pool’s circulation settings will help you maintain clean, healthy water all season long. Regular maintenance, proper chemical application, and monitoring will ensure that your swimming pool remains inviting and safe for everyone to enjoy.