The country is in the midst of a growing chlorine shortage. And that’s causing some pool supply stores to limit the amounts people can buy.

That could be a problem, since a lot of people added pools to their homes during the pandemic in lieu of a summer vacation. And a major chemical plant fire in Louisiana last August has created supply issues, as an estimated 800 tons of pool chlorine were lost.

That’s going to make it more expensive to keep pools clean. IHS Markit predicts chlorine prices could jump 70% this summer, after already doubling in some areas in the months following the fire at BioLab. The real effects of that fire haven’t been felt, as it took place right before Labor Day, when many pools close for the summer.

For example, a 50-pound bucket of three-inch stabilized chlorine tablets from the In the Swim brand used to sell for $109. It’s now $169.99 on Amazon. Many retailers, including Leslie’s Pool Supplies, are out of 50-pound buckets of certain chlorine tablets.

The upside for some pool owners is liquid chlorine still seems to be available on a fairly wide basis. While that, too, will be slightly more expensive, because of higher transportation costs, it could help prevent algae from taking over the country’s pools.

The problem could be felt especially strong in Northern states, which have had their pools closed until recently, due to a longer than usual winter. And the first step in reopening a pool is to shock it with chlorine. Pool supply and cleaning companies say they’re worried that just as people hoarded toilet paper last March, they could hoard chlorine this spring/early summer, meaning some people won’t be able to find it at all.