Chlorine tablets go in a floater, skimmer basket, or chlorinator — never loose in the water

Chlorine tablets dissolve slowly and release chlorine gas as they break down. If you drop them loose into your pool, they sink to the bottom, create a concentrated chemical spot that can damage the pool floor and liner, and release chlorine unevenly. Instead, tablets belong in one of three devices that hold them in place and let water flow through at a controlled rate. Which one you use depends on your pool setup and how much you want to monitor the process.

The three main methods are a floating dispenser (floater), your skimmer basket, or a dedicated chlorinator installed on your filter line. Each has trade-offs in convenience, cost, and how evenly they distribute chlorine. Most residential pools use either a floater or the skimmer, since both are cheap and require no installation.

Key Takeaways

  • Never place chlorine tablets loose in the pool — they will sink, damage the floor or liner, and create uneven chlorine levels.
  • A floating dispenser (floater) is the cheapest option and works in any pool, but it drifts around and can get stuck against walls or in corners.
  • Your skimmer basket holds tablets safely and keeps them out of sight, but you must remove them before running the pump if your skimmer is not designed for tablets.
  • An in-line chlorinator mounts on your filter plumbing and distributes chlorine most evenly, but costs $200 to $500 and requires installation.
  • Check your tablet container for the recommended number of tablets based on your pool size and test your chlorine level twice a week to avoid over- or under-dosing.

Using a floating dispenser (floater)

A floating dispenser is a plastic cage or basket that bobs on the surface of your pool and holds one to three chlorine tablets. Water flows through the cage as it floats, dissolving the tablets gradually. Floaters cost $10 to $25 and work in any pool — above-ground, in-ground, saltwater, or freshwater.

The main drawback is that floaters drift with the current and wind. They often get pushed into corners or against the wall, which can bleach the pool deck or damage vinyl liners in that spot. If your pool has a strong return jet or sits in a windy location, the floater may spend more time in one corner than circulating. You can tie a rope to the floater and anchor it to the pool deck, but this requires checking it regularly to make sure the rope has not tangled or pulled it underwater.

To use a floater, open the cage, drop in one to three tablets (follow the container label for your pool size), close the cage, and set it in the water. Check it every few days and refill when the tablets are mostly dissolved. Remove the floater before heavy rain or if you are draining the pool.

Placing tablets in your skimmer basket

Your pool's skimmer is the intake opening on the pool wall where water gets pulled toward the filter. Inside is a removable basket that catches leaves and debris. Many skimmers are designed to hold chlorine tablets in that basket, so the tablets dissolve as water flows through on its way to the pump.

This method keeps tablets out of sight and prevents them from drifting. However, not all skimmers are rated for tablets — some have baskets made of thin plastic that can warp or crack from the chemical heat. Check your pool manual or the skimmer label to confirm it is safe for tablets. If your skimmer is not rated for tablets, using them anyway can damage the basket and clog the pump.

If your skimmer is rated for tablets, place one to three tablets directly in the basket (follow the label for your pool size). The tablets will dissolve as the pump runs. You must remove the tablets before you turn off the pump for the day, because stagnant water in the skimmer can cause the tablets to dissolve too fast and create a chemical pocket. Check the basket every few days and replace tablets as they dissolve.

Installing an in-line chlorinator

An in-line chlorinator (also called a feeder or erosion feeder) is a plastic chamber that mounts directly onto your pool filter plumbing, usually between the filter and the return line. Tablets go inside the chamber, and water flowing back to the pool passes through them, dissolving them at a steady rate. This method distributes chlorine most evenly because the water is already being circulated by the pump.

In-line chlorinators cost $200 to $500 plus installation, which typically runs $100 to $300 if you hire a pool technician. They require cutting into your plumbing and gluing PVC fittings, so this is not a beginner DIY job unless you have plumbing experience. Once installed, they are low-maintenance — you straightforward drop tablets into the top chamber every week or two and let the system run.

The main advantage is precision: you can adjust the flow rate on some models to release chlorine faster or slower, and the even distribution means fewer dead spots with low chlorine. The main disadvantage is upfront cost and the fact that you cannot easily remove the chlorinator if you want to switch methods later.

How many tablets to use and when to replace them

The number of tablets depends on your pool size and the tablet strength. Most residential tablets are 3 inches in diameter and weigh about 8 ounces. The container label will specify how many tablets to use for pools of different sizes — for example, "one tablet per 10,000 gallons per week" or "two tablets per 20,000 gallons per week." Follow the label exactly, because using too many tablets will raise chlorine to unsafe levels and using too few will leave your pool vulnerable to algae.

Check your tablets every two to four days. As they dissolve, they shrink and eventually disappear. When a tablet is mostly gone (about the size of a quarter), remove it and add a fresh one. Do not wait until the tablet is completely dissolved, because the dispenser will then be empty and your chlorine level will drop.

Test your pool's chlorine level twice a week using a test kit or test strips. The safe range is 1 to 3 parts per million (ppm). If your level is too high, remove a tablet or reduce the number you are using. If it is too low, add a tablet or move to a faster-dissolving method like an in-line chlorinator.

Safety and storage tips

Chlorine tablets are corrosive and can burn skin and eyes. Always wear gloves and eye protection when handling them. Never touch a tablet with wet hands, and never inhale the dust or fumes. Store tablets in a cool, dry place away from sunlight, heat, and moisture — a sealed plastic container in a garage or shed works well. Keep them away from children and pets.

Never mix chlorine tablets with other pool chemicals, especially acids or algaecides. This can cause a dangerous chemical reaction. If you need to use multiple chemicals, add them to the pool at different times and wait at least 24 hours between applications.

If a tablet breaks or crumbles, do not try to use the pieces. Dispose of them in a sealed bag in the trash, or contact your local hazardous waste facility for instructions. Never pour them down a drain.

Troubleshooting low or high chlorine levels

If your chlorine level stays low even with tablets in the dispenser, the tablets may not be dissolving fast enough for your pool size. This happens in large pools or pools with heavy use. Move to an in-line chlorinator, which dissolves tablets faster, or add a second floater or skimmer tablet. You can also switch to liquid chlorine or powder chlorine for faster results, though these require more frequent dosing.

If your chlorine level is too high, remove the tablets when ready and let the pool sit for 24 to 48 hours. Chlorine naturally breaks down in sunlight, so running the pump during the day will help. Do not add more tablets until the level drops to the safe range. If the level stays high after two days, you may have added too many tablets — use fewer next time.

Cloudy water or algae growth despite tablets in the dispenser usually means the tablets are not dissolving fast enough or the dispenser is stuck in a corner where water is not flowing through it. Check that your floater is moving freely, that your skimmer basket is not clogged, or that your in-line chlorinator is not blocked. If the problem persists, test your water chemistry — chlorine is only one part of pool balance, and low pH or alkalinity can prevent chlorine from working effectively.

Frequently Asked Questions

Can I use chlorine tablets in a saltwater pool?

No. Saltwater pools use a salt chlorine generator (salt cell) that produces chlorine from salt, so adding tablets will over-chlorinate the water and damage the cell. If you have a saltwater pool, do not use tablets. Stick to the salt system your pool came with.

What happens if a chlorine tablet falls to the bottom of the pool?

It will create a concentrated chemical spot that can bleach or crack the pool floor or liner. Remove it when ready using a pool net or skimmer. If the damage is already done, drain that section and repair it, or have a pool technician assess the damage. Always use a dispenser to prevent this.

Can I put chlorine tablets in the pump basket instead of the skimmer?

No. The pump basket is designed to catch debris, not dissolve chemicals. Tablets will damage the basket and can clog the pump impeller. Use only the skimmer basket if your skimmer is rated for tablets, or use a floater or in-line chlorinator instead.

How long does one chlorine tablet last?

A standard 3-inch tablet typically lasts 3 to 7 days, depending on water temperature, pool size, and how much the pool is used. Warmer water and heavy use speed up dissolution. Check your tablets every few days and replace them as they shrink.

Do I need to remove chlorine tablets before swimming?

No, as long as your chlorine level is in the safe range (1 to 3 ppm), the pool is safe to swim in. The tablets will continue to dissolve and maintain the level. However, if you just added tablets or the level is above 3 ppm, wait until it drops before swimming.