How to use chlorine in your hot tub

How to use chlorine in your hot tub - Click to enlarge

There are several disinfection methods by chemical treatment: chlorine, bromine and active oxygen. Chlorine has the advantage of being long lasting (it remains active for several days in a clean spa), taking effect immediately, and being inexpensive and effective, even at very low concentrations.

Are you treating your spa with chlorine or do you want to treat your spa with chlorine? Here is some information that may help you.

After draining or restarting the spa

If you're changing the water or if your spa has been off for a while, it is possible that biofilm has developed in the piping. You must therefore start with a cleaning using the Ahh Some to remove it. You can find the instructions on how to remove biofilm right here! It also explains how to make sure it doesn't come back (cause no one likes biofilm).

Regular treatment

You got rid of the biofilm? Yay! Now you can start on the regular treatment. If necessary, fill the spa with water, and follow these steps:

  • Start by adding non-Chlorine Shock, at a rate of 15g per cubic meter of water. This will eliminate the bacteria present in the water.
  • Then add the chlorine in granules or effervescent tablets directly to the spa or diluted in a bucket of water beforehand. For quantities, allow 15 g per cubic metre of water for granules or 5 effervescent tablets per cubic metre of water.

Ideally, you should check your free chlorine levels every day, just before swimming. This rate must be between 1 and 3 ppm (the conversion from ppm to mg/l is easy: 1 ppm = 1 mg/l).

Two measurement methods are possible: with Aquacheck or InstaTest test strips (a fast but imprecise method) or with an analysis kit containing DPD1 tablets, which allows more accurate measurements.

One teaspoon of HTH granulated chlorine in a clean 1000-litre spa will increase the rate by 2 ppm. If chlorine level is 0: the water is no longer disinfectant and bacteria have started to proliferate. If the level has been at 0 for only a few hours, you can "catch up" with your water by adding a shock product, such as active oxygen. If the rate has been at 0 for several days, the situation is more serious because there is biofilm.

"Shock" your water regularly

The use of shocking agents is important, since chlorine will act against bacteria each time the spa is used, but it will gradually become saturated (free chlorine will react with the bacteria to form combined chlorine instead, which smells and isn't effective). Shocking with non-Clorine shock the water will destroy some of the combined chlorine.

Check the pH value

Chlorine is very sensitive to the pH of your water, you still need to adjust it ideally to ensure good treatment stability. A reminder, a good pH is between 7.0 and 7.6.

  • If the pH is too low you will have to use pH plus
  • If the pH is too high you will have to use pH minus

If you notice that the TAC (total alkalinity) of the spa is too low, add a little pH stabilizer.

You can also find the main products needed for processing in the form of boxes.

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