Add tablets directly to a floater or skimmer basket, never loose into the water

Chlorine tablets dissolve slowly and should never be dropped loose into your pool. Instead, place them in a floating chlorine dispenser (a plastic cage that bobs on the surface) or in your pool's skimmer basket (the catch-all box that pulls water toward the filter). Both methods let the tablet dissolve gradually as water circulates around it. The floater gives you more control over how fast the chlorine releases; the skimmer basket is simpler if you already have one, but the chlorine will dissolve faster because more water moves through it.

Never put tablets in the deep end and walk away. They can damage vinyl liners if they sit in one spot, and they dissolve unevenly, leaving some areas over-chlorinated and others under-protected. A floater or skimmer keeps the tablet moving and the chlorine distributed.

Key Takeaways

  • Place one tablet in a floating dispenser or skimmer basket; do not drop tablets loose into the pool water.
  • Check your pool's chlorine level before adding a tablet, because over-chlorination can irritate skin and damage equipment.
  • Replace or add a new tablet when the previous one shrinks to about half its original size, usually every 3 to 7 days depending on sun and water temperature.
  • Keep the floater or skimmer basket in an area with good water circulation so the tablet dissolves evenly and chlorine spreads throughout the pool.
  • Store tablets in a cool, dry place away from other chemicals, because chlorine reacts with many substances and can cause fires if mixed.

Check your chlorine level before you add a tablet

Test your pool water with a test kit or test strips before dropping in a tablet. You are looking for a free chlorine reading between 1 and 3 parts per million (ppm) for a residential pool. If your level is already above 3 ppm, wait a day or two and test again before adding more chlorine. Over-chlorination makes the water smell harsh, stings eyes and skin, and can corrode metal equipment faster.

Test strips are the fastest method: dip one in the water for a few seconds, pull it out, and compare the color to the chart on the bottle. A liquid test kit takes a few minutes longer but is often more accurate. Both cost between five and fifteen dollars and last through many tests.

Use a floating dispenser for easier control

A floating chlorine dispenser is a plastic cage, usually round or rectangular, that holds one or two tablets and floats on the surface. You open the cage, drop in a tablet, close it, and set it on the water. As the pump circulates water, it flows through the cage and dissolves the tablet gradually. The cage keeps the tablet from sinking and damaging the pool floor or liner.

The main advantage is control: you can pull the floater out if the chlorine level gets too high, and you can see at a glance whether the tablet is still there or nearly gone. The main disadvantage is that it takes up space on the surface and can get in the way during swimming. Floaters cost between eight and twenty dollars and last several seasons if you rinse and dry them after each use.

Use your skimmer basket if you do not have a floater

Your pool's skimmer is the box-shaped opening on the pool wall where water gets pulled toward the filter. Inside is a removable basket that catches leaves and debris. You can place a chlorine tablet directly in this basket instead of using a floater. The tablet will dissolve as water flows through on its way to the filter.

The advantage is simplicity: no extra equipment to buy or store. The disadvantage is speed—the tablet dissolves faster in the skimmer because more water moves through it, so you may need to replace it more often than you would with a floater. Also, you cannot see the tablet without opening the skimmer, so you might forget to replace it until the chlorine level drops. If your skimmer basket is full of leaves, empty it first so water can flow freely around the tablet.

Replace the tablet when it shrinks to half size

A standard chlorine tablet is about the size of a hockey puck and weighs roughly 8 ounces. As it dissolves, it shrinks. When it is down to about half its original size, remove it and drop in a new one. This usually happens every 3 to 7 days, depending on how much sun your pool gets, how warm the water is, and how much the pool is used. Warmer water and more sun speed up dissolution.

Do not wait until the tablet is completely gone to replace it. By then your chlorine level may have dropped too low to keep the water safe. Check the tablet every few days by looking at the floater or opening the skimmer basket. If you are not sure whether it is time to replace it, test the water—if the chlorine level is below 1 ppm, add a new tablet right away.

Store tablets safely away from other pool chemicals

Keep your chlorine tablets in a cool, dry place—a garage shelf or storage closet works well. Do not store them in direct sunlight or in a damp basement, because moisture and heat break down the tablets and make them less effective. Keep them in their original container or in an airtight plastic bucket with a tight-fitting lid.

Never store chlorine tablets near other chemicals, especially acids, algaecides, or shock treatments. Chlorine reacts with many substances and can start a fire if mixed. Keep tablets away from fertilizers, pesticides, and anything flammable. Store them out of reach of children and pets. If you spill tablets, sweep them up when ready and dispose of them according to your local hazardous waste guidelines—do not throw them in the trash.

Troubleshoot common tablet problems

If your chlorine level stays low even after you add a tablet, the tablet may not be dissolving. Check that the floater or skimmer basket is in an area with good water circulation—if it is stuck in a corner or against the wall, water may not flow around it evenly. Move the floater to the center of the pool or make sure the skimmer basket is clear of debris. Also check that your pump is running; if the pump is off, water is not circulating and the tablet will not dissolve.

If your chlorine level spikes too high after adding a tablet, you may have added one too soon or the water is very warm and the tablet is dissolving faster than expected. Remove the floater or tablet from the skimmer and let the pool sit for a day. Test again before adding another tablet. If this happens often, try using a floater instead of the skimmer, because you have more control over how fast the tablet dissolves.

Frequently Asked Questions

Can I put a chlorine tablet directly in the pool without a floater or skimmer?

No. Tablets dissolve unevenly and can damage vinyl liners or pool surfaces if they sit in one spot. They also create pockets of over-chlorinated water. Always use a floater or skimmer basket to keep the tablet moving and the chlorine distributed evenly.

How many tablets should I add at once?

Start with one tablet in a floater or skimmer basket. Test your chlorine level after 24 hours. If it is still below 1 ppm, add a second tablet. Most residential pools need one tablet every 3 to 7 days, not multiple tablets at once.

What if I forgot to replace the tablet and the chlorine level is too low?

Add a new tablet right away and test the water again after 24 hours. If the level is still low, you may need to use a faster-acting form of chlorine like liquid chlorine or shock treatment while you wait for the tablet to dissolve. Your pool store can recommend the right product for your pool size.

Do chlorine tablets work in cold water?

Yes, but much more slowly. Tablets dissolve faster in warm water, so in spring or fall when the water is cool, you may need to replace tablets less often. In winter, if you close your pool, you do not need chlorine tablets at all.

Can I use chlorine tablets in a hot tub or spa?

No. Tablets are designed for large pools and dissolve too slowly for the smaller volume and higher temperature of a hot tub. Hot tubs need faster-acting chlorine like granules or liquid chlorine. Check your hot tub manual for the correct chlorine type.