Opening an inground pool takes 4 to 6 hours of hands-on work spread across a weekend, plus 48 to 72 hours for water chemistry to balance and the pool to clear. The process is the same every year: clear and remove the cover, reinstall equipment, top up the water, restart circulation, balance chemistry, and shock the pool.
Before You Start: Inground Pool Opening Prep
Open the pool when daytime temperatures stay around 70°F for several days. Plan to open 2 to 3 weeks before you actually want to swim, since chemistry needs time to balance.
Gather supplies before starting. The basic toolkit covers a drop test kit, pool brush and telescopic pole, vacuum head, garden hose, cover pump or wet-dry vac, channel locks and screwdrivers for unions and deck anchors, silicone lubricant, and basic chemicals (liquid chlorine, pH adjusters, alkalinity increaser, plus anything else your last test showed was needed). Filter cartridges, sand, or DE may also need replacing if the filter media is past its service life.
Step 1: Pump and Remove the Pool Cover
Inground pools usually use either a solid safety cover anchored to the deck or a water-bag tarp cover. Both need to be cleared of debris before removal.
Pump standing water off the top with a cover pump or wet-dry vacuum, then sweep or skim leaves and debris off the surface. Send the cover water to the lawn or a storm drain — never back into the pool, since it carries dirt, organic matter, and unbalanced chemistry that can take days to clear out.
For solid safety covers, unscrew the deck anchors and lift the cover off slowly with one or two helpers, since these covers are heavy and awkward when wet. For tarp covers held down by water bags, drain and remove the bags first, then peel the cover off carefully so trapped debris does not slide into the pool.
Hose the cover down, let it dry fully, fold it loosely, and store it dry. A damp cover stored tight develops mildew. Skim the pool surface immediately to catch anything that fell in during cover removal.
Step 2: Reinstall Equipment and Check Plugs
Inground pools have more equipment to reset than above-ground pools.
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Remove winter plugs from each return jet, skimmer, and main drain (if accessible)
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Reinstall return jet eyeballs, aiming them slightly downward and away from the skimmer to create circulation
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Reinstall skimmer baskets and pump basket
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Reattach drain plugs to the pump, filter, and heater
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Reinstall ladders, handrails, and any pop-up cleaner heads
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Inspect pump unions, lid seals, and o-rings for cracks or dryness, and lubricate o-rings with silicone lubricant if they look dry
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Inspect filter media for wear, tears, or compaction, and replace if past its lifespan
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Walk the equipment pad and check for visible damage to plumbing or PVC lines from freezing
Also check the deck and coping. Inspect tiles, grout, and coping stones for cracks or shifts from winter freeze cycles. Catching this early prevents bigger repairs later in the season.
Step 3: Top Up the Water Level (And Why You Should Never Drain It)
Inground pools need water at the middle of the skimmer opening to operate properly. Below that point, the pump pulls air and breaks prime. Above that point, surface skimming becomes inefficient. Use a garden hose to top up after winter evaporation.
Critical safety note: never fully drain an inground pool without professional guidance, especially in areas with high groundwater. The water in the pool acts as a counterweight against hydrostatic pressure pushing up from below. An empty pool can lift, crack, or pop out of the ground entirely. If you genuinely need to drain for repairs, work with a pool professional who can install a hydrostatic relief valve or coordinate timing with groundwater conditions.
Step 4: Restart the Pump, Filter, and Heater
Fill the pump basket with water before starting to help the pump prime faster. Open all valves and turn on the pump. It may take a minute or two to draw water and fully prime.
If your pool was winterized with antifreeze in the plumbing, set the multiport on the filter to backwash and run for 1 to 2 minutes to flush the antifreeze out before the system circulates the rest of the pool. Then switch to filter mode for normal operation.
Once the pump is running, release trapped air at the filter until water flows steadily. Walk the equipment pad and check every connection for drips, sprays, or air bubbles in return jets. Listen for rattling or a high-pitched whine, which usually points to air still in the system.
Restart any additional inground equipment in this order:
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Heater: Check the pilot or igniter, condensate drain, and gas/electrical supply before starting. Modern heaters have a startup sequence that takes a few minutes
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Salt chlorine generator: Leave off until water has fully circulated for at least 24 hours and water temperature is above 55 to 60°F
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Automation system (Pentair, Hayward, Jandy): Reset the time clock, schedules, and any temperature or chemistry sensors
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Pool lights: Reset the GFCI on the panel and confirm the lights work before swimmers are in the water
Step 5: Test and Balance Water Chemistry
Run the pump for at least an hour after restarting before testing, so the water has mixed evenly. Use a quality drop test kit or fresh strips covering free chlorine, pH, total alkalinity, calcium hardness, and cyanuric acid.
Adjust in this order: alkalinity (target 80 to 120 ppm), then pH (7.4 to 7.6), then calcium hardness (200 to 400 ppm), then cyanuric acid (30 to 50 ppm). Wait at least an hour between adjustments and retest before adding more. For a deeper look at each chemical and dosing, see our pool opening chemicals guide.
Step 6: Shock the Pool and Run the Filter
Once chemistry is balanced, shock the pool to oxidize winter organic load. Add liquid chlorine at dusk so UV does not burn it off before it can work. Dose to roughly 10 to 20 ppm free chlorine. For most inground pools (15,000 to 25,000 gallons), that is 1.5 to 2.5 gallons of 10% liquid chlorine.
Run the pump continuously for 24 to 48 hours after shocking. Backwash sand or DE filters when pressure climbs 8 to 10 PSI above the clean baseline, since dead organic matter loads filters quickly during recovery. Brush and vacuum the floor as debris settles. Retest free chlorine and pH 24 hours later before considering the pool ready.
After Opening: First Week Inground Pool Care
The first week stabilizes chemistry and clears the last of the winter debris. Test water every two days, skim daily for pollen and fresh debris, brush walls and floor every two to three days, and clean the filter when pressure rises. Wait until free chlorine drops below 5 ppm before using a robotic cleaner, since shock-level chlorine can damage seals and motors over time.
Inground pools have larger water volumes and more surface area than above-ground pools, so the first week of vacuuming takes meaningful effort. A robotic pool cleaner like the iGarden Pool Cleaner M1-AI can make routine pool care much easier. Designed with strong suction, smart navigation, and reliable traction, it helps clean floors, walls, slopes, and waterlines while reducing the time and effort needed for manual pool maintenance. For finer debris, the optional dual-layer filter can be added in the recommended cleaning mode to help capture smaller particles and keep the water looking clearer.
Common Inground Pool Opening Problems
Pump Will Not Prime
Usually means water level is too low or air is leaking into the suction side. Confirm water is at the skimmer midpoint, then check the pump lid seal, basket, and unions for tight fit. Empty and reseat the basket, lubricate the lid o-ring, and try again. Persistent priming problems often point to a small crack in the suction-side plumbing that needs professional repair.
Heater Will Not Start
Gas heaters need gas, electricity, and steady water flow to ignite. Confirm the gas valve is open, the breaker is on, and the pump is running before troubleshooting the heater itself. Modern heaters display error codes — write down what you see and check the manual. Common spring issues are wasp nests in the burner area or condensate drain blockages.
Cloudy or Green Water After Shocking
Some cloudiness after shocking is normal and clears within 24 to 48 hours of continuous filtration. If the water is heavily green or stays cloudy after 48 hours, the pool likely needs a second round of shocking at full dose, plus a manual vacuum to waste so dead algae bypasses the filter and goes straight out. Vacuum-to-waste mode is faster and more thorough than letting the filter handle it.
Salt Cell Showing Low Salt Warning
Wait 24 hours after adding salt before testing or running the cell. Salt takes time to dissolve and circulate, especially in cold water. If the warning persists after 24 hours, test salt levels manually rather than trusting the cell sensor, which can drift over a winter.
Get More From Your Pool This Season
Opening your pool marks the beginning of swim season, but it can also be an opportunity to get more value from your pool beyond casual swimming and relaxation. If your pool is too short for lap swimming, a swim jet can create a continuous current that allows you to swim in place for fitness and endurance training.
The iGarden Swim Jet X Series offers a portable, battery-powered alternative to traditional built-in swim jets. It attaches directly to the pool edge without major construction or plumbing work, making it suitable for homeowners who want to add swim training, water exercise, or family fun to an existing pool. After opening and balancing your pool, a swim jet can be an easy way to expand how you use it all season long.
iGarden Portable Swim Jet X
Best-in-Class Water Flow: AI Inverter Tech delivers the strongest water flow in its class. 1-Min Setup: No drilling, no renovation. Clamp the jet and go. All in One: Training, playing, relaxing, experience the freedom of unlimited swimming.
FAQs
How long does it take to open an inground pool?
Hands-on time is typically 4 to 6 hours spread across a weekend. Including time for chemistry to balance and water to clear, the full timeline runs 48 to 72 hours from cover off to swimmable. A green or debris-loaded pool can extend that to a full week.
How much does it cost to open an inground pool?
DIY opening typically costs $200 to $500 in chemicals and supplies, depending on what your test results show is needed. Professional pool services charge $300 to $600 for a basic opening, with extras for heater startup, automation setup, or heavy cleanup. Hiring a professional makes sense the first time or if your equipment is complex, while DIY usually pays off after the first season.
How do I open my inground pool for the first time?
First-time openings of a brand-new pool require full doses of alkalinity increaser, calcium hardness increaser, cyanuric acid, and salt (for saltwater pools), since the water starts at zero on each. Run the filter continuously for 48 to 72 hours during initial balancing. For an inherited pool you are opening for the first time, follow the same process but start with a thorough equipment inspection and a full water test, since you do not know how the previous owner closed it.
Can I open my inground pool myself?
Yes, most owners can complete the full process in a weekend if equipment is in working order. Hire a professional if you suspect leaks, freeze damage to plumbing, heater problems beyond a reset, or if you have a complex automation or saltwater system you are not familiar with.
Should I drain my inground pool to clean it before opening?
No, almost never. Inground pools should not be fully drained without professional guidance because water acts as a counterweight against groundwater pressure. An empty pool can lift, crack, or pop out of the ground. Top up to the skimmer midpoint and clean the pool with the water still in it.
How much chlorine do I need to open an inground pool?
Dose to 10 to 20 ppm free chlorine for the opening shock. For a typical 20,000 gallon inground pool, that is roughly 2 gallons of 10% liquid chlorine. Use liquid chlorine rather than cal-hypo if calcium hardness is already at the high end.
When should I activate the salt chlorine generator?
Wait until water temperature is consistently above 55 to 60°F, salt has fully dissolved and circulated for at least 24 hours, and free chlorine is in the target range from a manual shock. Starting the generator before these conditions are met can damage the cell or trigger low-salt errors.