How to Leave Your Pool for a Vacation (1 to 3 Weeks)
Before you leave, balance the water, bring free chlorine to the top of your normal range, and set up a tablet floater or feeder a week ahead, or ask someone to add chlorine while you're gone. A pool that loses 2 ppm a day uses about 14 ppm of chlorine in a 7-day trip, so one dose before you leave will not last.
Always follow your product’s label directions. Pool and spa chlorine, bromine, shock and algaecides are EPA-registered pesticides: use products labeled for pool or spa use, and don’t swim or soak until levels are within the limit on your product’s label. If this page and a label disagree, the label wins.
On this page (10 sections)
The calculator shows how long your chlorine will last on its own, how much chlorine the pool will use while you're away, and how many 90% trichlor tablets it would take to replace it. The daily loss in the example is a placeholder: measure your own (see below), because every other result depends on it.
How long your chlorine will last
Chlorine lasts until it falls to the minimum for your stabilizer (cyanuric acid, CYA) level. In the example, CYA is 40 ppm, so the minimum is 3 ppm. Starting at 4 ppm and losing 2 ppm a day, the pool drops below 3 ppm in about half a day. That is why "add extra chlorine and go" does not work for more than a weekend.
Raising chlorine far above your normal range before a trip is not the answer either. Most chlorine labels limit swimming above a certain level, often 4 ppm, and a high dose also burns off faster in sun and heat. Use the calculator to plan steady chlorine while you're away instead. The minimum for other CYA levels is on pool chlorine levels.
Measure your daily loss. Test free chlorine (FC) in the evening and again the next evening, with no swimmers and no chlorine added in between. The difference is your loss per day. Do it on a sunny day, since sunlight breaks down more chlorine than anything else. If the pool loses more than 1 ppm overnight, something is using chlorine (often early algae): fix that before you leave. See chlorine not holding.
One week before you leave
- Test everything: FC, pH, total alkalinity (TA), CYA, and calcium. Fix anything out of range now, so you have time to retest.
- Set up the chlorine source you'll rely on (floater, inline feeder, salt cell, or a helper) and run it for the whole week.
- Check that FC holds. Test every day or two. Adjust the floater opening, feeder dial, or salt cell output until FC stays in your normal range.
- Clean the filter and empty the skimmer and pump baskets.
- Check the pump timer and the water level.
The day before you leave
- Brush the walls and floor, vacuum, and skim.
- Bring pH to 7.4–7.6.
- Bring FC to the top of your normal range for your CYA, no higher than the swim limit on your chlorine label.
- Top up the water to the normal level (midway up the skimmer faceplate for most skimmer pools, or the level in your manual), since it will evaporate while you're away.
- Refill the floater or feeder.
- Lock the gate, secure or remove the ladder of an above-ground pool (as Pool Safely advises whenever the pool is not in use), and put away toys that attract children.
Floaters, feeders, and stabilizer build-up
Trichlor tablets are the usual way to keep chlorine going while you're away, because they dissolve slowly. In the example, replacing 14 ppm over 7 days takes about 4.4 tablets of 90% trichlor at 200 g each (1.95 lb in total). A floater's output depends on its opening and on water flow, so the only way to know it matches your loss is to test for a week before you go.
The drawback is stabilizer. Trichlor adds about 0.6 ppm of CYA for every 1 ppm of chlorine (PHTA). Those tablets add about 8.4 ppm of CYA, and the CYA stays after you come back. A few trips a summer can push CYA high enough that your chlorine minimum climbs with it. Test CYA when you're back, and see how to lower CYA if it gets too high. Tablet sizes and counts for normal use are on the chlorine tablets calculator.
Inline feeders have a dial for the same reason: Hayward's feeder manual says to check the chlorine level daily and adjust the dial. Some feeders take extensions that hold more tablets for a longer trip. Don't put tablets in the skimmer basket; Embassy PoolCo's skimmer guide warns against it in capital letters, because concentrated chlorine sits in the plumbing whenever the pump stops. And never put any other chemical in a floater or feeder that has held trichlor.
Pump, timer, and water level
- Leave the pump on its timer. Moving water carries chlorine from the floater or feeder to every part of the pool and keeps debris moving to the filter. Hayward's feeder manual says not to shut the pump down for extended periods while the feeder holds tablets. Run times are on the pump run time calculator.
- Water level. If the level drops below the skimmer opening, the pump can draw in air and run dry. In hot, dry weather, a pool can lose a lot of water in a week; ask your helper to check it.
- Salt pools. Set the cell output so FC holds during the test week, and make sure the salt level is in the range your cell needs.
One, two, or three weeks away
| Time away | Chlorine | Someone should |
|---|---|---|
| A long weekend | FC at the top of your normal range when you leave; floater or salt cell running | Not needed in most pools |
| One week | Floater, feeder, or salt cell tested for a week beforehand | Check the water level and baskets once |
| Two weeks | Same, with the floater refilled halfway through | Test FC and pH and refill the floater |
| Three weeks or more | A helper adding chlorine, or a pool service | Test and add chlorine at least twice a week |
This plan is our suggestion, based on how fast chlorine is used; there is no official schedule. Heat, sun, storms, and heavy leaf fall all make chlorine run out sooner. A pool service is the most reliable choice for long trips in hot weather.
What to ask your helper to do
Write it down and leave the test kit, the chlorine, and the measuring cup in one place:
- Empty the skimmer and pump baskets.
- Check the water level; top up to the normal level you showed them.
- Test FC and pH. Write the readings and the date on the sheet.
- If FC is below the minimum for your CYA, add the amount of liquid chlorine you wrote on the sheet. Work it out in advance with the liquid chlorine calculator.
- Refill the floater. Never add anything else to it.
- Call you, or a pool service, if the water is cloudy or green.
When you get back
Test before anyone swims. The CDC advises testing pool water at least twice a day while the pool is in use, so start testing again as soon as you return. If the water is clear and FC is above the minimum for your CYA, go back to your normal routine. If it is cloudy or green, chlorine ran out: see cloudy pool water or how to clear a green pool, and treat it with a product labeled for that use, following its label.
Safety
Store chlorine and acid apart, out of reach of children and your helper's children. Never mix chemicals or put them in the same floater. Don't swim while chlorine is above the limit on your label. While you're away, keep the pool gate locked and any cover secured; a pool is a drowning hazard even when no one is using it. Poison Control: 1-800-222-1222. Always follow the product label.
FAQ
How long can a pool go without chlorine?
Only until free chlorine falls below the minimum for its CYA level, which in sun and heat can be less than a day. After that, algae can start within days. Measure your own daily loss to know your number.
Should I shock my pool before going on vacation?
Not to make chlorine last. A high dose burns off in sun and heat and may be above your label's swim limit. Bring FC to the top of your normal range and keep a steady chlorine source running instead.
Should I leave my pool pump on while on vacation?
Yes. Leave it on its normal timer. Circulation spreads the chlorine from the floater or feeder and keeps the filter working.
How many chlorine tablets do I need for a week away?
It depends on your gallons and daily loss. In the example, 14 ppm of chlorine over 7 days takes about 4.4 tablets of 90% trichlor at 200 g each. Enter your own numbers above.
Sources
- CDC, Home pool and hot tub water treatment and testing: cdc.gov
- CDC, Model Aquatic Health Code 2024, Annex (chlorine and CYA): cdc.gov (PDF)
- PHTA fact sheet, Water conservation during droughts (trichlor adds 0.6 ppm CYA per ppm chlorine): phta.org
- Hayward, CL100/CL200 chlorinator owner's manual (adjust the dial; don't shut the pump down for long periods): PDF
- Embassy PoolCo, Standard thru-wall skimmer owner's guide (no tablets in the skimmer; water level): PDF
- Pool Safely (CPSC), Summer safety barrier checklist: poolsafely.gov
- Minimum FC by CYA, chlorine used, tablets, and CYA added: our engine (trichlor 90%, +0.6 ppm CYA per ppm FC); see methodology.