The single most expensive mistake pool owners make when opening is following the wrong sequence. This guide gives you the exact order that works, the math behind the chemistry, and the specific errors that turn a $60 opening into a $400 problem.
QUICK ANSWERS
Q: When should I open my pool for summer?
A: Open when water temperature consistently stays above 60°F — not based on calendar date. In Florida and Texas, that means March or April. In the Midwest and Northeast, late April. Opening 2 weeks early costs roughly $15 in extra chlorine. Opening 2 weeks late can cost $200-400 in algae treatment.
Q: What chemicals do I need to open my pool?
A: Cal-hypo shock (68%), 3-inch trichlor tablets, polyquat 60 algaecide, pH decreaser (sodium bisulfate), and a 5-way test kit. Total chemical cost for a 15,000-gallon pool: $61-91 if chemistry is in range.
Q: How much shock do I need to open my pool?
A: For a clean pool: 1 lb of cal-hypo (68%) per 10,000 gallons raises free chlorine by approximately 5-7 ppm. For visible algae: 3-6 lbs per 10,000 gallons. Always shock after sunset — UV destroys unstabilized chlorine within 2 hours in direct sunlight.
Q: How long after opening can I swim?
A: Typically 24-48 hours after shocking, once free chlorine drops back to 1-4 ppm. Test before swimming — do not rely on time alone. Per PHTA guidelines, do not allow swimming until chlorine is at or below 4 ppm.
Q: What order do I add pool chemicals when opening?
A: Always in this order: (1) balance pH first, (2) adjust total alkalinity, (3) verify CYA below 80 ppm, (4) shock at night, (5) add algaecide the following morning once chlorine drops below 4 ppm. Adding shock before balancing pH wastes up to 80% of your chlorine.
Q: What is CYA and why does it matter when opening?
A: Cyanuric acid (CYA) is a stabilizer that accumulates from trichlor tablet use. Per the PHTA APSP-11 Standard, the ideal range is 30-50 ppm and the maximum is 100 ppm. Above 80 ppm, CYA reduces chlorine effectiveness significantly. Test CYA before shocking. If above 80 ppm, partial drain and refill before adding any chemicals.
Q: How much does it cost to open a pool?
A: For a 15,000-gallon pool opened from a clean winter close: $61-91 in chemicals. If the pool was neglected or improperly closed: $150-400+. Buying chemicals in bulk from a direct pool supply source saves $100-200 versus retail hardware stores for identical chemistry.
Key Terms Defined
These definitions follow the standards set by the Pool & Hot Tub Alliance (PHTA) and align with EPA-registered product labeling.
Free Chlorine (FC): The active, sanitizing chlorine available in pool water. Per PHTA guidelines, the target range for residential pools is 1.0-4.0 ppm. Below 1 ppm, bacteria and algae can establish within hours. Above 4 ppm, swimming is not recommended until levels drop.
Cyanuric Acid (CYA / Stabilizer): A UV protector added to pool water through every trichlor tablet dissolved. Per the PHTA APSP-11 Standard, the ideal range is 30-50 ppm and the maximum is 100 ppm. Above 80 ppm, CYA substantially reduces chlorine effectiveness. No chemical removes CYA — dilution by partial drain and refill is the only fix.
Total Alkalinity (TA): A buffer that prevents pH from swinging with every rain or bather event. Target: 80-120 ppm per EPA-registered product labeling. Low TA causes pH instability throughout the season.
Cal-Hypo (Calcium Hypochlorite): The standard pool shock. Available in 68% formulations (yielding 65% available chlorine) and 73% formulations (yielding 70% available chlorine). Adds no CYA. Must be pre-dissolved in a bucket before adding to the pool.
Breakpoint Chlorination: Raising free chlorine high enough — typically 10 times the combined chlorine reading — to completely destroy all chloramines and algae in a single treatment. Half-dosing a green pool leaves resistant algae behind.
When to Open Your Pool: Temperature Over Calendar
Most pool owners use Memorial Day as their trigger. That is the wrong metric.
Algae growth accelerates significantly when water temperature exceeds 60°F. A closed pool with no active chlorine is an environment where algae can establish before the cover even comes off. By the time you open in late May, you may already be fighting an established algae bloom.
| Region | Target Opening Window | Avg Water Temp Crosses 60°F |
| Florida, South Texas, Southern Arizona | Mid-March to early April | February-March |
| Gulf Coast, Carolinas, Georgia | Early to mid April | March-April |
| Mid-Atlantic, Tennessee, Oklahoma | Late April | April |
| Midwest, Great Plains | Late April to early May | Late April |
| Northeast, Pacific Northwest | Early to mid May | May |
Bottom Line: Open based on water temperature, not the calendar. The cost of opening 2 weeks early is roughly $15 in extra chlorine. The cost of opening 2 weeks late averages $200-400 in algae treatment chemicals and labor.
What You Need Before You Start: Complete Supply List
Every item below is needed before you begin. Running to the store mid-opening breaks the chemistry sequence and typically means buying retail what you could have ordered in bulk.
Chemicals (April 2026 pricing from direct pool supply sources):
| Chemical | Purpose | Amount for 15,000 gal | Approx. Cost |
| Cal-hypo shock (68%) | Sanitize and kill algae at opening | 3 lbs minimum | $12-18 |
| Chlorine tablets (3″ trichlor) | Ongoing sanitation after opening | 5-8 lbs first 2 weeks | $18-25 |
| Polyquat 60 algaecide | Prevent algae establishment | 1 quart | $15-22 |
| pH decreaser (sodium bisulfate) | Lower pH before shocking | 1-3 lbs | $8-14 |
| pH increaser (soda ash) | Raise pH if too low | 1 lb | $5-8 |
| Sodium bicarbonate | Raise total alkalinity if below 80 ppm | 2-4 lbs if needed | $6-10 |
| 5-way test kit | Measure all parameters before adding anything | 1 kit | $15-35 |
Bottom Line: Total chemical cost for a 15,000-gallon pool opened from a clean winter close: $61-91. The same quantities purchased at a hardware store retail typically cost $150-200. The chemistry is identical across sources — the price difference reflects retail overhead, not product quality.
Equipment:
- Submersible pump — to remove standing water from cover before pulling it
- Garden hose
- Skimmer net and pool brush — brush before shocking to expose algae on surfaces
- Vacuum head, hose, and pole
- Bucket for pre-dissolving shock — never add cal-hypo powder directly to pool
The Opening Sequence: 12 Steps in the Correct Order
✓ KEY FACT: The order of these steps is not interchangeable. Adding shock before balancing pH wastes up to 80% of your chlorine at pH 8.0. Adding algaecide while chlorine is above 4 ppm chemically deactivates it before it reaches any algae.
Step 1: Remove Standing Water from Cover Before Pulling It (Day 1)
A winter cover with 200 lbs of standing water dumps all of that — plus accumulated debris, organic matter, and algae spores — directly into your pool when pulled. Use a submersible pump to remove standing water first. Takes 20-40 minutes and saves hours of filtration work.
Pull the cover with two people, walking toward one end so debris stays on the cover rather than falling in. Lay flat on the deck, hose off, scrub, and dry completely before folding and storing. A wet cover stored in a bag grows mold and may be unusable by fall.
⚠ WARNING: Inspect the cover for tears before storing. A pinhole in October becomes a torn cover by March. Patch with cover repair tape or note for replacement before closing season.
Step 2: Reinstall All Equipment (Day 1)
Replace everything removed for winter:
- Return fittings and eyeball directionals
- Skimmer baskets — remove winterizing plugs from skimmer and return lines
- Drain plugs in pump housing and filter — check O-rings for cracking
- Pressure gauge on filter
- Ladders, handrails, diving boards
⚠ WARNING: Check every threaded fitting and union for cracks. Freeze-thaw cycles crack PVC fittings that look intact. A cracked 1.5″ union costs $4 to replace now. Finding the same crack after 2 weeks of pump operation can mean drained water, equipment damage, and $200+ in repairs.
Step 3: Fill to Proper Water Level (Day 1-2)
Target: midpoint of the skimmer opening.
- Too low: skimmer pulls air instead of water, which cavitates and damages the pump impeller
- Too high: skimmer efficiency drops and surface debris bypasses the basket
Step 4: Prime and Start the Pump — Check for Leaks (Day 2)
✓ KEY FACT: Fill the pump strainer basket with water from a garden hose before starting. A pump that runs dry for even 60 seconds can damage the mechanical seal. Seal replacement: $50-150. New pump: $400-1,200.
Start the pump and walk the full equipment pad for 10-15 minutes watching for leaks at every union, valve, and fitting. Set filter to FILTER position and run continuously through the entire opening process.
| Filter Type | Action Before Running | Why |
| Sand filter | Backwash 2-3 minutes until sight glass runs clear | Removes debris compressed during off-season |
| Cartridge filter | Remove cartridge, hose down thoroughly, reinstall | Compressed cartridge filters poorly until cleaned |
| DE filter | Backwash, then recharge with fresh DE powder | Old DE loses filtration efficiency over winter |
Step 5: Test All Five Parameters Before Adding Any Chemical (Day 2)
✓ KEY FACT: This step is skipped by most pool owners who go straight to shock. Testing first tells you exactly what is needed. Adding shock to high-pH or high-CYA water wastes money and time without solving the problem.
| Parameter | Target Range | Test Method | If Out of Range |
| Free Chlorine (FC) | 1.0-4.0 ppm | DPD test kit | Proceed with opening sequence |
| pH | 7.2-7.6 | Phenol red test tablet | Adjust before any other chemical addition |
| Total Alkalinity (TA) | 80-120 ppm | Titration test | Adjust after pH, before shocking |
| Cyanuric Acid (CYA) | 30-50 ppm (max 100 ppm per PHTA) | Turbidity test | If above 80 ppm: partial drain before shocking |
| Calcium Hardness | 200-400 ppm | Titration test | Low: add calcium chloride. High: partial drain. |
Source: PHTA free chlorine standard (1.0-4.0 ppm) and CYA maximum (100 ppm): PHTA Cal-Hypo Fact Sheet 2021
Source: PHTA CYA ideal range (30-50 ppm) and APSP-11 maximum (100 ppm): PHTA Water Balance Fact Sheet 2022
Bottom Line: Record all five numbers before touching a chemical. A pool that will not clear despite correct-looking chlorine levels almost always has undiagnosed high CYA. Test CYA before adding more shock.
Step 6: Balance pH to 7.2-7.4 First (Day 2-3)
pH controls how effective every other chemical is. In pools without cyanuric acid, chlorine at pH 8.0 operates at approximately 20% efficiency versus 63% at pH 7.2. This is the most important step in the sequence for pools without stabilizer.
| pH Level | Active Chlorine % (unstabilized pools) | Practical Implication |
| 7.0 | ~73% | Slightly acidic — watch for equipment corrosion over time |
| 7.2 | ~63% | Ideal for shocking — near maximum safe effectiveness |
| 7.4 | ~48% | Good for maintenance — most swimmer-comfortable |
| 7.6 | ~36% | Marginal — chlorine demand increases noticeably |
| 7.8 | ~27% | Poor — requires roughly 2x more chlorine for same effect |
| 8.0 | ~20% | Effectively non-functional for shocking in unstabilized pools |
⚠ IMPORTANT NOTE: These HOCl percentages apply to pools without cyanuric acid. In pools using trichlor tablets — which includes most residential pools — CYA is always present. In stabilized pools, the FC:CYA ratio has a greater influence on chlorine effectiveness than pH alone. Maintaining pH in the 7.2-7.8 range is still recommended for equipment protection, LSI balance, and swimmer comfort, but pH alone does not fully determine chlorine strength when CYA is present.
Source: CYA and pH interaction: Pool Help (citing Pickens 2017 research)
Bottom Line: Pools that sit closed over winter typically drift to pH 7.8-8.2. Get pH to 7.2-7.4 before shocking. At pH 8.0 in an unstabilized pool, you use $20 of chemical to get the sanitizing power of $4 used correctly.
Dosing Example: Lowering pH with Sodium Bisulfate
Pool volume: 15,000 gallons
Current pH: 8.1
Target pH: 7.3
Drop needed: 0.8 pH units
Dose: 1 lb sodium bisulfate per 10,000 gallons drops pH approximately 0.4 units
Calculation: (15,000 / 10,000) x 2 doses = 3 lbs total
Add 3 lbs dissolved in a bucket of water, broadcast around perimeter.
Wait 4 hours, retest before proceeding.
Never add more than 3 lbs at once — overshoot is difficult to correct quickly.
Step 7: Adjust Total Alkalinity (Day 2-3)
Total alkalinity stabilizes pH. Without adequate TA, pH bounces after every rain, bather event, or chemical addition — you spend the season chasing chemistry.
Dosing Example: Raising Total Alkalinity with Sodium Bicarbonate
Pool volume: 15,000 gallons
Current TA: 55 ppm (target: 80-120 ppm)
Increase needed: 35 ppm
Dose: 1.5 lbs sodium bicarbonate per 10,000 gallons raises TA by ~10 ppm
Calculation: (35 ppm needed / 10 ppm per dose) x (15,000 / 10,000) x 1.5 lbs
= 3.5 x 1.5 x 1.5 = approximately 7.9 lbs (round to 8 lbs)
Add in two doses of 4 lbs each, 4 hours apart.
Retest before proceeding to shock.
⚠ WARNING: Sodium bicarbonate sold as ‘alkalinity increaser’ at pool stores is identical chemistry to ARM & HAMMER baking soda. The pool store version typically costs 3-5x more per pound.
Step 8: Verify CYA Before Shocking (Day 2-3)
CYA is the most commonly skipped test and the leading cause of pools that stay green despite seemingly correct chlorine levels.
| CYA Level | Effect on Chlorine | Action Required |
| 0-20 ppm | Chlorine burns off within 2-3 hours of direct sunlight | Add cyanuric acid to reach 30-50 ppm before or after opening |
| 30-50 ppm | Optimal range per PHTA APSP-11 Standard | Proceed with shocking |
| 50-80 ppm | Somewhat reduced effectiveness — still workable | Proceed, monitor monthly |
| 80-120 ppm | Chlorine substantially less effective than readings suggest | Partial drain (1/3 of pool volume) and refill before shocking |
| 120+ ppm | Pool will not clear regardless of shock dose | Drain 50%+ and refill before any chemical treatment |
Source: PHTA APSP-11 Standard: CYA ideal range 30-50 ppm, maximum 100 ppm
Bottom Line: If your pool turned green last season despite adding chlorine, high CYA was the most likely cause. There is no chemical that removes CYA — dilution is the only fix.
Step 9: Shock the Pool at Night (Night of Day 3)
⚠ WARNING: NEVER add cal-hypo shock directly to the pool in powder form. Pre-dissolve each bag in a bucket of pool water first, then broadcast the dissolved solution while walking the pool perimeter. Undissolved cal-hypo bleaches vinyl liners, stains plaster, and creates white residue that takes days to filter out.
| Pool Condition at Opening | Cal-Hypo Dose (68%) | Per 10,000 Gallons |
| Clean water, routine opening | 1-2 lbs | 5-10 ppm chlorine boost |
| Slight haze, very light algae | 2-3 lbs | 10-15 ppm boost |
| Clearly green, visible algae | 3-4 lbs | 15-20 ppm boost |
| Dark green, heavy algae growth | 5-6 lbs | 25-30 ppm boost |
| Black-green, severe neglect | 6+ lbs + algaecide the next morning | Breakpoint chlorination required |
Worked Example: Shocking a 20,000-Gallon Pool with Visible Green Algae
Pool volume: 20,000 gallons
Condition: Clearly green, visible algae on walls and steps
Dose: 3 lbs cal-hypo (68%) per 10,000 gallons
Calculation: (20,000 / 10,000) x 3 lbs = 6 lbs total
Step 1: Brush all pool walls and floor before adding shock.
This exposes algae attached to surfaces to the chlorine.
Step 2: Pre-dissolve 2 lbs in a 5-gallon bucket of pool water.
Step 3: Walk the perimeter, broadcasting the dissolved solution.
Step 4: Repeat with remaining 4 lbs in two more buckets.
Step 5: Run pump overnight — minimum 8 hours continuous.
Step 6: Do NOT run automatic cleaner until water is visibly clearing.
Step 10: Run the Pump Overnight (Night Day 3 through Morning Day 4)
Minimum 8 hours of continuous circulation after shocking. 12 hours is better. Dead spots behind ladders, in corners, and near the main drain hold algae that only circulating chlorine reaches. Do not turn off the pump until morning.
Step 11: Add Algaecide the Following Morning (Morning Day 4)
⚠ WARNING: Wait until free chlorine drops below 4 ppm before adding algaecide. Quat-based and polyquat algaecides are chemically deactivated by high chlorine levels. Adding algaecide to water at 10+ ppm free chlorine means you spent $15-25 on a bottle that did nothing.
| Algaecide Type | Best For | Avoid If | Approx. Cost (2026) |
| Polyquat 60 | Opening treatment, all pool types, broadest safe use | Nothing — recommended for opening | $15-25/qt |
| Copper-based | Persistent green or black algae as follow-up treatment | Water chemistry still unbalanced — causes staining | $12-20/qt |
| Quat (ammonium) | Light weekly prevention maintenance | Heavy algae already present — foams badly at high doses | $8-15/qt |
Bottom Line: Polyquat 60 is the right call for opening. It does not foam, does not stain, and kills a broad spectrum of algae types. Add per label directions only after chlorine drops below 4 ppm.
Step 12: Run Filter Continuously and Retest on Day 5-6
The filter clears dead algae and chemical byproducts from the water. Watch the pressure gauge — when it rises 8-10 psi above the clean baseline, backwash or clean the cartridge. Opening a neglected pool may require backwashing 3-4 times in the first 48 hours.
| What You See on Day 5-6 | What It Means | Action |
| Water visibly clearing, all 5 parameters in range | Opening successful | Switch to regular maintenance schedule |
| Water still hazy, chlorine reads 1-4 ppm | Filtration still catching up | Run 24 more hours, retest |
| Water still green after 48 hours | Algae demand exceeded shock dose OR high CYA | Test CYA first, then re-shock at higher dose after brushing |
| Chlorine at zero morning after shocking | High CYA consuming chlorine, or active algae bloom | Test CYA immediately before adding more chemicals |
| Water clear but CYA now above 80 ppm | Tablets adding CYA faster than expected | Reduce tablet dose, test monthly, plan partial drain |
If X Happens, Do Y: Troubleshooting Opening Week
Why is my pool still green after shocking?
Three causes in order of likelihood:
- CYA above 80 ppm — chlorine is present but substantially locked up and less effective. Test CYA before adding anything else. If elevated, partial drain and refill before re-shocking.
- pH too high when you shocked — chlorine was less effective at the time. Lower pH to 7.2-7.4, then re-shock at the full dose.
- Shock dose was too low for the algae load — re-shock at 3-5x the standard dose, brush walls and floor first to expose all algae to the chlorine.
Why is my pool cloudy but chlorine is reading correctly?
Cloudiness with adequate chlorine is almost never a chlorine problem. The three most common causes:
- High calcium hardness (above 400 ppm) — calcium precipitating out of solution. Test hardness. Partial drain if severe.
- Clogged or dirty filter — backwash sand or DE filter, or clean cartridge. Check that pump is running at full flow.
- Fine particles in suspension after algae kill — run filter continuously and add a clarifier ($8-12). Resolves in 24-48 hours with good filtration.
⚠ WARNING: Adding more shock to a chemically balanced but cloudy pool wastes money and temporarily spikes chlorine to unsafe swimming levels. Diagnose the actual cause before adding any chemical.
Why did my pool turn green the day after opening?
Algae was already established before the cover came off. This happens when:
- CYA was above 80 ppm going into winter — chlorine never worked effectively last season, algae overwintered
- Pool was closed without adequate shock — algae went dormant and began growing as soon as temperatures rose above 60°F
- Cover had tears or unsealed gaps — light and airborne algae spores entered over winter
The fix: test CYA, adjust pH to 7.2-7.4, shock aggressively at 3-5 lbs per 10,000 gallons, brush before shocking, run pump continuously.
Why is my pump not priming after opening?
- Air leak in the suction line — check unions and fittings between skimmer and pump for hairline cracks. Even a small crack pulls enough air to prevent priming.
- Pump strainer basket not filled with water before starting — fill the basket fully from a garden hose, replace the lid firmly, then try again.
- Clogged impeller — debris from the off-season blocking water flow. Shut off power, remove pump lid, clear the impeller manually.
Can I add all my opening chemicals at the same time?
| Chemical | Add When | Minimum Wait Before Next Step |
| pH decreaser | After testing, before anything else | 4-6 hours, retest pH |
| Alkalinity increaser | After pH is in target range | 4-6 hours, retest TA |
| Shock (cal-hypo) | After pH and TA in range, at night | Run pump overnight — minimum 8 hours |
| Algaecide | Morning after shocking | Wait until FC is below 4 ppm |
| Chlorine tablets | After algaecide, in floater or feeder | Ongoing — check weekly |
What the Chemistry Actually Costs: Retail vs. Direct Supply Pricing
The chemistry in a $35 5-lb bucket of chlorine tablets from a hardware store is identical to the chemistry in a $130 50-lb bucket from a pool supply direct source. The active ingredient — trichloro-S-triazinetrione at 90% available chlorine — is a standardized commodity regulated by the EPA. What you pay extra for at retail is the shelf space, the smaller pack size, and the seasonal markup.
| Product | Hardware Store (retail) | Direct Pool Supply (bulk) | Season Savings |
| Chlorine tablets (50 lbs) | $165-200 (bought in 5-lb increments) | $100-130 (50-lb bucket) | $65-100 |
| Cal-hypo shock (24 lbs) | $120-150 (individual bags) | $75-110 (case of 24) | $40-75 |
| Algaecide (1 qt polyquat) | $25-35 | $15-22 | $10-13 |
| pH decreaser (10 lbs) | $30-40 | $18-28 | $12-22 |
| Total annual savings | $127-210 |
Bottom Line: For a pool owner buying the standard seasonal chemical supply, switching from retail hardware stores to a direct pool supply source saves $127-210 per season on identical chemistry. The 50-lb chlorine tablet bucket is the single highest-leverage purchase — approximately $2.10/lb direct versus $5.60-7.00/lb in 5-lb retail packs.
Where to Buy Opening Chemicals
Doheny’s Pool Supplies carries the full range of opening chemicals — cal-hypo shock, polyquat 60 algaecide, pH adjusters, and bulk chlorine tablets — with free shipping on orders over $50 and next-day delivery available on Doheny’s brand chemicals to most of the continental US. Family owned since 1967. Lowest price guarantee. Shop Doheny’s pool opening chemicals →
The 50-lb chlorine tablet bucket and the 24-bag case of cal-hypo shock are the two highest-leverage bulk buys for the opening season. See our Where to Buy page for direct links and current April 2026 pricing across all chemical categories.
External References
PHTA Cal-Hypo Fact Sheet (free chlorine standard 1.0-4.0 ppm): https://www.phta.org/pub/?id=07fd3498-1866-daac-99fb-8824a8f3147b
PHTA Water Balance Fact Sheet (CYA standard 30-50 ppm, max 100 ppm, trichlor adds 0.6 ppm CYA per ppm chlorine): https://www.phta.org/pub/?id=50ffe77d-1866-daac-99fb-9719108d1367
PHTA Liquid Chlorine Fact Sheet (pH 7.5 = 50% HOCl, EPA-specified FC 1.0-4.0 ppm): https://www.phta.org/pub/?id=0905861a-1866-daac-99fb-b239bf43994b
ICC/AQUA Magazine — Trichlor: The Dependable Pool Performer (product chemistry, CYA accumulation): https://aquamagazine.com/features/trichlor-the-dependable-pool-performer.html
Pool Help — pH and Chlorine Efficacy (Pickens 2017 research, CYA/pH interaction in stabilized pools): https://www.poolhelp.com/home/onbalance-research/onbalance-research/the-true-science-about-ph-chlorine-efficacy/
Opening Checklist: Print and Take to the Pool
Day 1:
- Standing water pumped off cover before removal
- Cover removed with two people, debris kept out of pool
- Cover cleaned, fully dried, inspected for tears, stored
- All return fittings, eyeballs, and winterizing plugs replaced
- Skimmer baskets installed
- Filter backwashed (sand/DE) or cartridge cleaned
- All fittings and unions checked for cracks
- Pool filling to midpoint of skimmer
Day 2:
- Pump primed (basket filled with water before starting)
- Pump running, no leaks at any fitting — watched for 15 minutes
- Filter set to FILTER position, running continuously
- All 5 parameters tested and recorded: FC, pH, TA, CYA, Calcium Hardness
- pH adjusted to 7.2-7.4 if needed (sodium bisulfate)
- Total alkalinity adjusted to 80-120 ppm if needed (sodium bicarbonate)
- CYA verified below 80 ppm — if above, partial drain before proceeding
Night of Day 3:
- Shock pre-dissolved in bucket before adding — never add powder directly
- Pool walls and floor brushed before shocking
- Shock added after sunset — walked perimeter while broadcasting dissolved solution
- Pump running overnight — minimum 8 hours
Morning of Day 4:
- Free chlorine tested — if below 4 ppm, algaecide can be added
- Polyquat 60 algaecide added per label directions
- Filter pressure checked — backwash if 8-10 psi above clean baseline
- Filter running continuously
Days 5-6:
- All 5 parameters retested
- Water visibly clearing — main drain visible from surface
- All parameters in range: FC 1-4 ppm, pH 7.2-7.6, TA 80-120 ppm, CYA 30-50 ppm
- Automatic cleaner deployed once water is visibly clear
- Tablet dispenser stocked and set for ongoing maintenance