How To Lower Combined Chlorine In Hot Tub?


There are three effective ways to lower combined chlorine in your hot tub: Superchlorination, supplemental/secondary sanitation, and using a non-Chlorine shocking oxidizer.

The best and most used procedure when lowering combined chlorine between these three is the Superchlorination of the Water.

Alternatively, you can opt to either use another non-Chlorine shocking oxidizer or supplemental and secondary sanitation (such as chlorine or bromine).

Also, other processes like UV pool sanitation and Ozone pool sanitation can also be used to reduce combined chlorine in your hot tub.

Overall, lowering combined chlorine in your hot tubs is essential as it enables you to have quality water as well as better air conditioning.

With that said, here is everything you need to know about combined chlorine.

Why is my combined chlorine so high?

The main reason why your combined chlorine is so high can be due to the presence of organic chloramines in your hot tub.

This condition mainly occurs when the combined chlorine content is predominately dichloramine and has low levels of monochloramine.

But first of all, what is Combined chlorine?

Well, combined chlorine refers to an intermediate breakdown product formed during the pool sanitizing process.

Typically, chlorine pools are associated with a certain smell which is, in fact, caused by combined chlorine.

And so, in general, higher combined chlorine means that you have higher combined chlorine levels than free chlorine.

What level of combined chlorine is too high?

Overall, the ideal chlorine level should stay between 1.0 and 3.0 ppm.

However, when it comes to combined chlorine, the level should remain below 0.2 ppm; higher than that will indicate higher combined chlorine levels.

Also, this means that your chlorine is, in fact, fighting a significant enough oxidant demand compound, such as ammonia, that its ability to keep sanitizing your hot tube is being compromised (dropping).

So, you must check to see the combined and free chlorine levels in your hot tub.

If the levels of combined chlorine are higher than free chlorine, then you are expected to clean your pool water by increasing the amount of chlorine.

Normally, combined chlorine is an important and reliable metric that tells us enough information about water safety in your hot tub.

What is the most effective way to lower combined chlorine levels?

Practically, there are several ways to lower combined chlorine levels in your hot tub or pool.

However, the most effective, widely used, and accepted practice to address higher combined chlorine issues is by far the Superchlorination practice.

Remember that higher combined chlorine means that the combined chlorine levels are higher than free chlorine.

Therefore, Superchlorination aims to restore relative balance by creating extra free chlorine.

How much shock is needed to reduce combined chlorine?

To ensure your Superchlorination (shocking) process is effective, then you will have to shock your hot tub by putting 10 times the amount of chlorine to combined chlorine in the water.

Basically, superchlorination is one way of shocking your pool, as it involves adding chemicals to reduce the combined chlorine levels. However, this practice has downsides since using 10X might be more than necessary, but the hot tub must not be used until you have restored the FAC levels.