There are a dizzying number of scenarios where your spa could get over-chlorinated. Maybe you set the chlorine container on the rim of the tub and your cat knocks it in (out of spite, of course). Or, maybe you misread the current level of free chlorine and put in more than needed. You get where I’m going with this.

The real question is: What do I do now? Have I just made a ghastly mistake that’s going to ruin my spa?
Nope. Let’s take a look at what to do if you (or your cat) have over-chlorinated your spa.
Determining How Much Cl Your Spa Needs
It wouldn’t be an informative article if I didn’t tell you how to figure out how much chlorine your spa needs in the first place, so here goes.

Test your water using your preferred test strips. The CDC (you remember those guys, right?) recommends between 1 and 3 ppm free chlorine to properly sanitize water. Keep in mind, if you’re using an alternative sanitizer such as Nature 2, you’ll need much less, just follow the instructions that came with the kit.
How to Reduce Chlorine Levels
There are 3 effective methods for reducing chlorine, should the unthinkable happen. Here are the methods I recommend trying in order:
- Let Cl levels reduce on their own – Sometimes the easiest solution is to do nothing. Simply leave the cover open and let the spa circulate. Generally, within a day or two the chlorine levels will deplete on their own.
- Refill with fresh water – You may not need to do a complete drain and refill. Often times refilling half of the spa with fresh water will get your levels where they need to be.
- Neutralize chlorine with Sodium Thiosulfate – This is widely available for pools, which happen to be much larger than hot tubs, so pay special attention to dosing instructions.
So, the big chlorine fiasco turned out to be a non-event. Want to get the full skinny on chlorine in hot tubs? I wrote an article about that right here.
This is a little off-topic, but there is an occasion where too much chlorine is good – to decontaminate your spa. Here’s a little article about that.
As always, any questions and our fabulous SpaDepot.com team is just a phone call or email away.