Do I Need to Drain My Green Pool? Step-by-Step Solution

Tools & Supplies Needed

Find on Amazon: Taylor K-2006C Pool Test Kit , Pool Brush with Telescopic Pole , Liquid Pool Chlorine

Quick Answer

In most cases, you do not need to drain your green pool. Green water is typically caused by algae growth, which can be effectively eliminated using the proven SLAM (Shock Level And Maintain) method. Draining should only be considered in extreme cases where the water is completely black, has been neglected for months, or when your Total Dissolved Solids (TDS) are extremely high.

When Draining IS Necessary

Before diving into the treatment process, let's identify the rare situations where draining might be your only option:

• Black or extremely dark water - If you can't see the bottom at the shallow end
• Structural damage visible - Cracks, staining, or deterioration that needs repair
• Contamination issues - Sewage backup, chemical spills, or hazardous materials
• Extremely high TDS - Over 3,000-4,000 ppm making chemical balancing impossible
• Multiple failed treatment attempts - After 2-3 weeks of proper SLAM with no improvement

Step-by-Step Green Pool Recovery Without Draining

Step 1: Test Your Water Chemistry

1. Use a reliable test kit like the Taylor K-2006C to measure current levels
2. Test for Free Chlorine (FC), pH, Total Alkalinity (TA), Cyanuric Acid (CYA), and Calcium Hardness (CH)
3. Record all readings - you'll need baseline numbers to track progress
4. If CYA is over 100 ppm, consider partial draining to dilute stabilizer levels

Step 2: Calculate Your Shock Level

1. Determine your shock level based on CYA reading using the FC/CYA chart:
2. CYA 30-40 ppm: Shock level 12-16 FC
3. CYA 50 ppm: Shock level 20 FC
4. CYA 60-70 ppm: Shock level 24-28 FC
5. Calculate chlorine needed: typically 1 gallon of 12.5% liquid chlorine per 10,000 gallons raises FC by 1.3 ppm

Step 3: Balance pH and Total Alkalinity

1. Lower pH to 7.2-7.4 using muriatic acid if above this range
2. Don't worry about raising low pH during SLAM - chlorine addition will naturally raise it
3. Adjust Total Alkalinity to 80-120 ppm for regular pools (60-80 for salt water generators)
4. Add 1.5 lbs of sodium bicarbonate per 10,000 gallons to raise TA by 10 ppm

Step 4: Begin the SLAM Process

1. Add enough liquid chlorine to reach your calculated shock level
2. Run your pump and filter 24/7 throughout the entire process
3. Brush all pool surfaces thoroughly - walls, steps, corners, and behind ladders
4. Clean or backwash your filter when pressure rises 8-10 psi above clean pressure
5. For sand filters, backwash daily during heavy algae treatment

Step 5: Maintain Shock Level

1. Test FC levels every 2-4 hours during daylight
2. Add more liquid chlorine to maintain your shock level - algae consumes chlorine rapidly
3. Continue brushing twice daily to break up algae colonies
4. Don't add algaecides - they can interfere with chlorine effectiveness and cause foaming

Step 6: Monitor Progress and Test for Completion

1. Water should begin clearing within 24-48 hours
2. Perform the Overnight Chlorine Loss Test (OCLT) once water is clear
3. Test FC levels before bed and again first thing in the morning
4. Loss should be 1 ppm or less overnight when algae is dead
5. Complete three consecutive successful OCLTs before ending SLAM

Why Avoid Draining When Possible

Draining your pool creates several risks and expenses:

• Structural damage - Pools can crack or "pop" out of the ground without water weight
• Equipment damage - Pumps can run dry and burn out
• Higher costs - Refilling costs $200-600 depending on size and water rates
• Chemical restart - You'll need to rebalance entirely new water
• Time loss - Refilling and rebalancing takes 2-3 days minimum

Special Considerations

Sand Filter Users: Consider flocculent (floccing) if your sand filter can't clear fine particles. Add 4-8 oz of aluminum sulfate per 10,000 gallons, let settle 24 hours, then vacuum to waste.

Cartridge Filter Users: Have spare cartridges ready - you'll need to clean or replace them frequently during treatment. Rotate between sets while cleaning.

DE Filter Users: Expect to break down and clean your filter multiple times. Don't add new DE until the algae is completely dead.

Timeline Expectations

Most green pools clear within 3-7 days using proper SLAM technique. Factors affecting timeline include:

• Severity of algae bloom
• Filter type and condition
• Consistency in maintaining shock levels
• Thoroughness of brushing
• Starting chemical balance

Safety Warning: Always add chemicals to water, never water to chemicals. Wear safety goggles and gloves when handling pool chemicals. Ensure proper ventilation when using muriatic acid.