How to Clean a Pool: Weekly Maintenance, Shock Treatment, and Water Chemistry

Frequently Asked Questions

How often should I clean my pool?

Skim and check chemistry at least twice a week during swimming season. Brush walls and vacuum the floor once a week. Run your pump 8-12 hours per day to keep water circulating. In high summer with heavy use, you may need to test chemistry daily.

What chemicals do I need to maintain a pool?

You need chlorine (tablets or liquid), pH increaser (sodium carbonate) and decreaser (muriatic acid or sodium bisulfate), alkalinity increaser (sodium bicarbonate), calcium hardness increaser (calcium chloride), and cyanuric acid (stabilizer). Shock (calcium hypochlorite or sodium dichloro) is separate from your regular chlorine routine.

How do I shock a pool and when should I do it?

Dissolve or broadcast shock around the pool perimeter at dusk (UV degrades it fast). Use 1 lb per 10,000 gallons for weekly maintenance shock, double or triple the dose for algae or heavy contamination. Shock after heavy rain, after a pool party, after any algae appearance, and weekly throughout summer. Wait until chlorine drops below 5 ppm before swimming — usually 8-24 hours.

Why is my pool water green?

Green water is algae. It grows when chlorine drops below 1 ppm, typically after heavy rain dilutes your water, after a period of neglect, or when stabilizer (CYA) is too low and chlorine degrades in sunlight. Fix it by shocking at 3x normal dose, brushing every surface, running the pump 24/7, and filtering until clear — usually 24-72 hours.

How do I lower or raise pool pH?

To raise pH, add sodium carbonate (soda ash) — start with 6 oz per 10,000 gallons, retest after 4 hours. To lower pH, add muriatic acid or sodium bisulfate — start with 1 quart per 10,000 gallons for muriatic acid, always add acid to water (never the reverse), broadcast it near the return jets with the pump running. Retest before adding more.

What is the correct chlorine level for a pool?

Free chlorine should stay between 1-3 ppm for residential pools. At 1 ppm or below, algae and bacteria can establish quickly. Above 5 ppm, the water is irritating to eyes and skin and unsafe for swimming. Stabilized chlorine (with CYA present) needs to stay at the higher end of the range — aim for 2-3 ppm.

How do I clear cloudy pool water?

Cloudy water has four main causes — treat in this order: (1) Test and adjust chemistry first: low chlorine is the most common cause — shock the pool at 1 lb per 10,000 gallons and retest in 8 hours; high pH clouds water even with adequate chlorine — lower to 7.4. (2) If chemistry is balanced and water is still cloudy, run the pump 24 hours per day until clear and clean the filter (backwash D.E. or sand, rinse cartridge). (3) Add a water clarifier (polymer flocculant) — it causes fine particles to clump and sink or catch in the filter; run 24 hours, vacuum the floor. (4) If clarifier fails, add a flocculant (floc): broadcast across the pool, turn the pump OFF for 24 hours to let particles settle to the floor, then vacuum to waste (not back through the filter). Most cloudy pools clear in 24–48 hours with one of these approaches.

How do I close a pool for winter?

Winterizing prevents freeze damage and algae growth while the pool is covered. Steps: (1) Balance water chemistry one last time: pH 7.4–7.6, alkalinity 100–120 ppm, chlorine 1–3 ppm, add a double dose of algaecide. (2) Lower the water level below the skimmer inlet (6–18 inches below the tile line, depending on your cover type). (3) Blow out the plumbing lines using a wet/dry vacuum or air compressor — any water left in pipes freezes and cracks them. (4) Add pool antifreeze to skimmer and return lines if in a freeze-prone region. (5) Plug all returns and the skimmer opening. (6) Drain and store the pump, filter, heater, and chlorinator — do not leave water in any equipment. (7) Install the winter cover and secure tightly. Skipping step 3 (blowing lines) causes the most expensive winterization failures.

Cleaning a pool weekly: (1) Skim the surface for leaves and debris. (2) Brush walls and steps from the waterline down toward the drain.

A neglected pool can cost $500 or more to restore — algae treatments, enzyme cleaners, filter media replacement, and possibly a professional service call. A consistent 30-minute weekly routine prevents all of it. Pool maintenance is not complicated, but it is regular. Skip a week in July and you may come back to green water. Stay on schedule and the pool runs itself.

What You Need

These are the tools and chemicals for a complete pool maintenance kit. Each link searches Amazon for the product category with the fixupfirst affiliate tag.

• Pool test kit or test strips — test strips are faster; liquid kits are more accurate
• Skimmer net with telescoping pole — the pole also attaches to the brush and vacuum head
• Pool brush for walls and floor — nylon for vinyl liners, stainless-steel for plaster or concrete
• Manual vacuum head and hose — connects to your skimmer port
• Pool shock (calcium hypochlorite) — keep 10-20 lbs on hand through summer
• 3-inch chlorine tablets — for your floater or automatic feeder

Beyond these, you’ll want a supply of pH up, pH down, alkalinity increaser, and cyanuric acid. Buy these at a pool supply store — they’re often cheaper there than on Amazon and you can get your water tested for free while you’re there.

Weekly Maintenance Routine

The full routine runs 20-40 minutes depending on pool size. Do it in this order — it matters.

Step 1: Skim the Surface

Use the net to remove leaves, bugs, pollen, and debris from the water surface. Work from the far end toward the skimmer basket so circulation pulls debris that direction. Check and empty the skimmer basket and pump basket while you’re at it — clogged baskets strain the pump and reduce filtration.

Time: 5-10 minutes

Step 2: Brush Walls and Floor

Attach the brush to the telescoping pole. Brush the walls from the waterline down, then the floor toward the main drain. Pay attention to corners, steps, and any shaded areas where algae starts first. Brushing disturbs debris so the filter can catch it and breaks up biofilm before it turns into visible algae.

For plaster or concrete pools, use a stiff nylon or combination brush. For vinyl liner pools, use nylon only — wire bristles will tear the liner.

Time: 5-10 minutes

Step 3: Vacuum the Floor

Attach the vacuum head to the pole, connect the vacuum hose, and prime it by submerging the hose end at a return jet until water fills it. Connect the other end to the skimmer suction port (or dedicated vacuum port) and vacuum slowly — moving too fast stirs up debris instead of catching it.

If the pool has heavy sediment, vacuum to waste (bypass the filter) so you don’t clog the filter media. You’ll lose a few inches of water level doing this, so top off with the garden hose afterward.

Time: 10-15 minutes

Step 4: Test the Water

Use test strips or a liquid test kit to check free chlorine, pH, total alkalinity, and (weekly or bi-weekly) calcium hardness and CYA. Read the results in natural light — LED lighting distorts colors on test strips. Write down results so you can track trends.

Time: 5 minutes

Step 5: Adjust Chemistry

Add chemicals based on your test results, one at a time. Add each chemical with the pump running, wait 30 minutes, and retest before adding the next adjustment. Never mix chemicals together before adding to the pool.

Always add acid to water, not water to acid — pour it slowly near a return jet, not directly into the skimmer.

Step 6: Run the Pump

Run the pump 8-12 hours per day during summer, minimum 6 hours in cooler weather. Ideally run it during the hottest part of the day when chlorine degrades fastest. A timer on your pump makes this automatic and saves electricity by running it off-peak.

Water Chemistry Targets

Keep all parameters in range at the same time. A pool with perfect chlorine but wrong pH still doesn’t sanitize effectively — pH affects how much of your free chlorine is actually active.

Parameter	Target Range	Low Risk	High Risk
Free Chlorine	1 - 3 ppm	Algae, bacteria growth	Eye/skin irritation, unsafe to swim
pH	7.4 - 7.6	Chlorine less effective, corrosion	Scale buildup, cloudy water
Total Alkalinity	80 - 120 ppm	pH bounces wildly	Scale, cloudy water
Calcium Hardness	200 - 400 ppm	Etching plaster, foam	Scale, rough surfaces
Cyanuric Acid (CYA)	30 - 50 ppm	Chlorine degrades in sunlight fast	Chlorine lock above 100 ppm

CYA is the most overlooked parameter. Without stabilizer, direct sunlight destroys 50% of your free chlorine within one hour. With proper CYA levels (30-50 ppm), chlorine is protected and lasts through the day.

How to Test and Adjust Chemistry

Test Strips vs. Liquid Test Kits

Test strips are fast — dip, wait 15 seconds, compare to the chart. They’re accurate enough for routine weekly checks. A 7-way strip tests chlorine, bromine, pH, alkalinity, hardness, cyanuric acid, and total dissolved solids simultaneously.

Liquid test kits (Taylor K-2006 is the standard) are more accurate, especially for free vs. combined chlorine and cyanuric acid. Use a kit for monthly thorough checks and when troubleshooting a persistent problem.

Most pool supply stores offer free computerized water testing — bring a water sample (collected at elbow depth, away from returns) and they’ll give you a full printout with dosing instructions.

Adjusting pH

pH drifts up naturally as carbon dioxide off-gasses from the water. Check it twice a week in summer.

To raise pH: add sodium carbonate (soda ash). Start with 6 oz per 10,000 gallons. Broadcast it with the pump running, wait 4 hours, retest.

To lower pH: add muriatic acid or sodium bisulfate. For muriatic acid, start with 1 quart per 10,000 gallons if pH is significantly high. Pour slowly near a return jet. Never add more than the recommended dose at once — over-correction causes a crash.

Adjusting Alkalinity

Alkalinity is the buffer that keeps pH stable. If pH keeps swinging despite corrections, alkalinity is probably the culprit.

To raise alkalinity: sodium bicarbonate (baking soda). Add 1.5 lbs per 10,000 gallons to raise alkalinity by 10 ppm. Broadcast it around the pool with the pump running.

To lower alkalinity: muriatic acid, added to a concentrated area near the pool’s surface with the pump off, then circulate after 30 minutes. This is the same chemical as pH down — the technique differs.

Adding Cyanuric Acid

Add CYA once at the start of the season. Dissolve it in a bucket of warm water first, then pour along the pool edge. It takes 24-48 hours to register fully on a test. CYA doesn’t dissipate — it only leaves when water is diluted by rain or splash-out. If CYA climbs above 80 ppm, partially drain and refill to dilute it.

When and How to Shock the Pool

Shocking means adding a large dose of oxidizer — usually calcium hypochlorite or sodium dichloro — to burn off chloramines (combined chlorine), kill algae, and restore free chlorine fast.

When to Shock

• After heavy rain (dilutes chlorine, introduces organics)
• After a pool party with heavy bather load
• When free chlorine drops below 1 ppm
• At the first sign of green or cloudy water
• Weekly during peak summer — especially if the pool is used daily

How to Shock

1. Test the water first. Know where pH is — calcium hypochlorite raises pH, so pre-lower pH to 7.2 before shocking for better effectiveness.
2. Shock at dusk or night. UV light destroys calcium hypochlorite rapidly. Night application gives the chemical hours to work before sunlight hits.
3. Use 1 lb per 10,000 gallons for maintenance shock. For algae treatment, use 2-3 lbs per 10,000 gallons.
4. Pre-dissolve granular shock in a bucket of water before adding to the pool — never add dry shock directly to the water over a vinyl liner.
5. Broadcast it around the perimeter near the walls.
6. Run the pump continuously for at least 8 hours after shocking.
7. Test before swimming — wait until free chlorine is below 5 ppm, usually 8-24 hours.

Liquid chlorine (sodium hypochlorite) is an alternative shock option. It doesn’t raise pH as much as cal-hypo and doesn’t need pre-dissolving, but it’s heavier to haul and has a shorter shelf life.

Dealing with Green Water

Green water is almost always algae. The fix requires multiple steps in sequence — skipping any step usually means the problem comes back.

Step 1: Test and adjust pH to 7.2. Shocking at the right pH is more effective.

Step 2: Brush every surface thoroughly. Algae clings to walls, steps, and corners. Break it loose so the shock and filter can work.

Step 3: Shock at 3x the normal dose. For a 20,000-gallon pool with heavy algae, that’s 6 lbs of cal-hypo. Add it at dusk.

Step 4: Run the pump continuously. Do not turn it off until the water clears.

Step 5: Add a pool algaecide. A copper-based or quaternary algaecide as a follow-up treatment helps prevent regrowth. Add it 24 hours after shocking.

Step 6: Vacuum dead algae. It will settle as grey-green sediment. Vacuum to waste so you don’t clog the filter.

Step 7: Backwash or clean the filter. After a heavy algae treatment, the filter loads up fast. Backwash a sand or DE filter, or rinse cartridges.

The water typically clears in 24-72 hours with this approach. If it stays green after 72 hours with proper chlorine levels, test CYA — if it’s above 100 ppm, chlorine becomes ineffective (chlorine lock) and a partial drain and refill is required.

Robotic vs. Manual vs. Automatic Suction Cleaners

Pool cleaning equipment falls into three categories. All three clean the floor — they differ in cost, coverage, and maintenance.

Manual Vacuum

The cheapest option ($30-100 for head and hose). You push it yourself, connected to the skimmer suction. Takes 15-20 minutes per session. Best for: infrequent cleaners, smaller pools, or homeowners who want full control over what gets cleaned.

Automatic Suction Cleaners

Devices like the Hayward Navigator or Zodiac MX6 connect to the skimmer suction and crawl the floor randomly ($200-600). They run unattended while you do other things. Best for: moderate budgets, pools that collect mostly fine sediment rather than large debris. Limitations: they tax the pump, miss corners, and can get stuck on irregular shapes.

Robotic Cleaners

Self-contained units with their own motor and filter bag ($600-1,500+). They scrub, vacuum, and filter independently of your pool pump. Better coverage, cleaner results, and they don’t stress your filtration system. Top brands include Dolphin, Polaris, and Hayward. Best for: regular pool users who want the least manual labor and the best cleaning results.

A robotic cleaner doesn’t replace weekly brushing — it supplements it. You still need to brush corners and steps the robot misses, and you still need to skim and manage chemistry.

Seasonal Opening and Closing Basics

Opening (Spring)

1. Remove and store the cover. Clean it before folding away.
2. Reinstall equipment removed for winter (returns, ladders, steps).
3. Fill to proper water level.
4. Start the pump and inspect for leaks.
5. Shock heavily — winter allows chloramines and algae spores to accumulate.
6. Test and balance all chemistry before swimming.
7. Run the pump for 48 hours continuously after opening shock.

Closing (Fall)

1. Balance chemistry one week before closing — proper pH and alkalinity protect surfaces over winter.
2. Shock and add algaecide.
3. Lower water level below the skimmer and return jets (prevents freeze damage).
4. Blow out and plug plumbing lines in freeze-prone climates.
5. Remove, clean, and store ladders, returns, and skimmer baskets.
6. Install the cover securely with water bags or anchors.

In mild climates where freezing isn’t a risk, you can keep the pump running on a timer through winter at reduced hours (4-6 hours/day) instead of doing a full closing.

Related Reading

• Swimming Pool Installation Cost
• Best Robot Vacuums for Homeowners