Why Does the Chlorine Level Keep Dropping in my Hot Tub?

Having the right amount of chlorine or other sanitizer in your hot tub is vital. It ensures that the water is bacteria-free and safe. But what happens when the Chlorine levels keep dropping and what are the right Chlorine levels to keep the hot tub safe?

I decided to check it out and here is what I found out:

So, why does the chlorine level keep dropping in my hot tub? Hot tub Chlorine levels will naturally decay over time. It is normal to have to top up your Chlorine levels. If Chlorine is declining quickly check your PH levels, shock the hot tub and make sure that the water isn’t overly contaminated.

Why does Chlorine decay?

Basically Chlorine gets used up as it eats up contaminants and kills bacteria. It can also be prone to attack by the sun’s UV rays and it will, over time, dissipate. into the atmosphere making the familiar Chlorine smell.

This is why, when you add Chlorine to your hot tub, you can add it to a strong level (about 8 – 10 ppm) so that it is strong enough to kill everything and to sanitize the water. After a period of time, the Chlorine will get used up and will drop to a lower level (2 – 4 ppm) which is a safe level for bathing in.

You can check your chlorine levels with a simple test strip test. Try these test strips from Amazon.

Eventually, the Chlorine level will drop right down and you will have to add more to sanitize the water again. You will need to wait again for the levels to drop and so the cycle continues. This is why a lot of people add Chlorine and shock their hot tubs after each usage. Whilst they are not in the water the higher levels Chlorine can get on with the job of disinfecting the water before dropping back down to a safe level for the next bathing session.

Remember the effective addition of Chlorine (or bromine) is vital to the health of your water and is the only sanitization system recommended by the Centres of Disease Control and Prevention.

Once you get into a regular pattern of adding Chlorine like this it is very easy to remember and effective.

How can I check the Chlorine levels in my hot tub?

As the music in this video suggests, checking the Chlorine levels in your hot tub is easy:

Make sure that you keep the test strips nice and dry and that you hold them by the edges to prevent contamination by the moisture and oils on your skin. The video also suggests that 45 mins will be enough time for the Chlorine levels to drop to a safe level but this will vary on a number of variable factors and it could take much longer.

Remember to read the side of the Chlorine pack carefully and add the right amount of Chlorine for your particular situation. Not adding enough puts you at risk of the water not being sanitized effectively and adding too much could just mean a very long wait for it to reduce down to safe levels.

Why does the Chlorine in my hot tub always need topping up?

So, the Chlorine level in your hot tub will need to be topped up regularly and this is normal. But what happens if the levels start to drop really quickly or all of the Chlorine seems to get used up really fast and you can’t seem to maintain a safe 2 – 4 ppm level?

There are a number of possibilities:

Incorrect PH levels – Having the correct total alkalinity and PH levels for your water is an absolute bedrock of successful hot tub water chemistry. Many hot tub water problems stem from not regular checking and adjusting PH levels and, with a simple daily routine, can often be avoided.

Chlorine is particularly sensitive to PH imbalance and, if your PH levels are out your Chlorine will work much less efficiently. This could mean that you need to add much more than usual to get the correct levels and/or it could lead to the Chlorine being used up really quickly and not maintaining a safe base level.

Sunshine – Chlorine is very susceptible to the UV rays of sunshine and, if the weather has changed and your hot tub is in direct strong sunlight a lot of the time this will mean that your Chlorine levels will drop more quickly.

You could try using a sunshade, sail or umbrella to try to keep the worst of the sunshine off the surface of the water. Also remember to put the hot tub cover on when it’s not in use. It is a good idea to remove it immediately after shocking the hot tub as it will allow the initial chemical vapor to dissipate and stop it from attacking the hot tub cover’s vinyl cover but, after a short amount of time it ti best to replace it.

Heavy usage – Chlorine’s job is to keep the water in your hot tub clean and fresh so, it stands to reason that, if you use the hot tub a lot the Chlorine will have to work harder and will deplete sooner. If your Chlorine levels have suddenly started to plummet and you seem to be needing to add a lot of Chlorine to the hot tub have you been using it more often or staying in for longer?

Remember that the ideal pattern of usage is for the hot tub to be used and then for Chlorine to be added. It’s then best to leave the hot tub for a while for the Chlorine to do it’s job of killing bacteria and dissipating down to safe levels before the hot tub is being used for bathing again.

If you are having problems with your Chlorine levels have you been sticking to this pattern or has the hot tub may be been used several times before being shocked again?

Contaminated water – Chlorine will also disappear quite quickly if it is having to battle really dirty or contaminated water. Did someone get into the hot tub before showering or spill some food or drink into the hot tub? Maybe the bathing costumes had washing powder or conditioner still in them or the lid has been left off the hot tub for a while and dirt and debris has blown in.

Anything that makes the hot tub water dirty and therefore the Chlorine have to work harder will mean that the Chlorine levels will need topping up more frequently.

Just to be on the safe side it’s always worth taking the time to have a shower before getting into the hot tub. Try to remove all moisturizer, shampoo, soap, dirt, sweat and anything else that could contaminate the hot tub water. Finally, have a good rinse in plain water before getting into the hot tub.

So, very often the hot tub will simply have an increased demand for Chlorine based on the prevailing conditions. You should check the Chlorine levels frequently and be prepared to top up the levels as needed. Bear in mind that if your levels go too low then you are at risk of bathing in unsanitary dirty water – not nice or healthy!

How long does it take for Chlorine levels to drop in a hot tub?

This is a bit of a how long is a piece of string question but, generally speaking, it will take from an hour or two up to 24 hours for the Chlorine levels to go down. It’s really important that you test the water before going and that the Chlorine levels are between 2 and 4 ppm.

Obviously the more Chlorine you need to add to the hot tub in the first place the longer it will take for the levels to drop. It is also important that you allow the water and Chlorine to circulate by having the jets on to avoid getting any really concentrated areas of Chlorine in the water.

What alternative sanitizers are there to Chlorine for my hot tub?

Chlorine is a powerful chemical. It’s great at it’s job of cleaning water but many people simply don’t like the idea of sitting in such a concentrated soup of chemicals. Luckily, there are a few alternative ways of sanitizing your hot tub, many of which are more environmentally friendly than using Chlorine. Many of these systems are highly efficient and do away with the small and associated irritation of Chlorine.

However, you need to bear in mind that you may well still need to use some Chlorine with these alternative systems as well. Your Chlorine usage may well dramatically go down but you may not be able to do away with it altogether.

For public hot tubs the recommendation is still to use Chlorine as it is pretty much guaranteed to keep your water bacteria-free. However, it is entirely your choice and, by using an alternative sanitizer you will be able to cut down on your Chlorine usage but you must make sure that the water in your hot tub is still clean and fit for use. If your hot tub is only used relatively lightly you shouldn’t have a problem and you will be able to enjoy Chlorine-free bathing. But, if you are a heavy hot tub user then you will need to take more care and consider combining alternative solutions with the Chlorine as well.