What to Do With Leftover Chlorine Tablets When You Close Your Pool
As the weather cools off and pool season winds down, most DIY pool owners end up with the same little problem: a bucket that's half full of chlorine tablets and no idea what to do with them. Do you use them up before you close the pool? Toss them in the floater and forget about it all winter? Store them for next year?
The short answer is that leftover tablets are worth keeping, as long as you handle them the right way. Here's how to finish out the season and store what's left so it's ready to go again next summer.
Give Your Pool One Last Dose Before You Close It
Before you cover the pool, test your water and bring your chlorine level to a normal range. A good rule of thumb during the season is about one 3-inch tablet per 10,000 gallons of water per week, adjusted for how many people are swimming, how hot it's been, and how much sun the pool gets. Always confirm with a test kit or strips rather than guessing, especially right before closing.
You don't need to load up on chlorine right before you close up. The goal is a clean, balanced pool going into the off-season, not a big final dose.
Take the Floater or Feeder Out Before You Cover Up
This is the step people skip, and it's the one that causes the most damage. A tablet floater or feeder that's left running all winter can drift into a corner, get stuck against a step, or sit in one spot on a vinyl liner or plaster wall for months. When that happens, the concentrated chlorine in that one spot can bleach or stain the surface long before spring.
Pull the floater and feeder out before you put the cover on. If your pool needs an off-season sanitizer, that's a separate winterizing product made to dissolve slowly and evenly, not a job for leftover trichlor tablets sitting in a floater all winter.
How to Store the Tablets You Have Left
Trichlor tablets hold onto most of their strength for a long time when they're stored properly, so there's no reason to toss what you don't use. A few basics make the difference between tablets that are still good next spring and a hard, crumbling mess:
Keep them in the original container
The bucket or tub they came in is designed to hold up to the chemical and keep moisture out. Keep the lid on tight between uses.
Find a cool, dry, ventilated spot
Somewhere in the 50 to 70°F range is ideal. Avoid a hot shed, a garage that bakes in direct sun, or anywhere damp. Heat and humidity are what break tablets down early.
Keep them off the floor and away from metal
A shelf works better than the ground, both to avoid standing water and to keep the container away from metal shelving or tools, which can corrode from chlorine fumes over time.
Store them away from other pool chemicals
Trichlor is an oxidizer, so keep it separated from pool shock, acid, and other chemicals. Mixing the wrong products, even just from a spill or leak, can cause a dangerous reaction.
Keep them locked up and out of reach
A cabinet or shed that kids and pets can't get into is worth the extra step, especially if the tablets will be sitting for several months.
When Spring Rolls Around Again
Once you open the pool back up, take a look at what's left in the bucket. Properly stored tablets should look and feel the same as when you bought them, no crumbling or strange odor. Test your water before you add anything, then get back into your normal weekly routine.
If you're running low or starting from empty, that's a good time to restock. ClaroBlu sells 3-inch trichlor chlorine tablets direct to homeowners at wholesale pricing, the same rate we offer pool service professionals, with no distributor markup in between. It's an easy way to start the season without paying retail shelf prices.
A little care at closing time and a proper spot to store what's left is really all it takes. Handle it right, and the tablets sitting in your shed this winter will be just as ready to work next June as they are today.