How a zero reading on your swimming pool test kit can be misleading.
If your test kit is reading you have no chlorine in your swimming pool it may be because it is actually too high, not because it it too low. When you test for chlorine it is a type of colorimetric test, which relies on a color change to read your results.
The chlorine in your pool is similar to the bleach you use for your laundry and liquid swimming pool chlorine is the same exact chemical. Extreme chlorine levels can bleach your colorimetric test results giving a false reading of zero.
How Determine if Your Chlorine is So High its Bleaching Your Test Kit.
If you are getting a zero reading on your free chlorine it is either because you have no chlorine in your pool or you have a chlorine level so high that it is actually bleaching the color change that is supposed to be occurring in the cliometric tests.
The easiest way to find out if this is your problem is to dilute the swimming pool water and test again. We recommend that you try two different dilutions. First a fifty percent dilution. If it still says you have no chlorine try diluting to a solution that is one part swimming pool water one part filtered or RO water. If that doesn’t produce a result than try using one part swimming pool water 4 parts filtered or RO water.
We recommend that you use filtered or RO water as the filter will remove any free chlorine that is in your tap water so long as the carbon in that filter is not exausted. In some areas chlorine is used in small amounts to disinfect the water while it travels from the treatment plant to your home, which would need to be adjusted for if not removed.
- Mix a half cup pool water with a half cup filtered water
- Test for Free chlorine
- Multiply the result by two.
- If you still get a zero reading test again
- This time take 1 half cup pool water and 4 cups filtered water mix them and test again.
- Multiply the result by 5.
If you are still getting a zero reading there is most likely no free chlorine in you swimming pool.
How to Proceed if Your Chlorine is too high.
Levels where the chlorine bleaches your test kit get into the extreme range. This water is not suitable to swim in. When your chlorine is this high it is likely that bathing suits, tile lines and hair will be bleached as well.
The first thing you need to do is temporarily quit dosing chlorine. Quit dosing until you get the levels under 5ppm. For residential coustomers we recommend keeping your free chlorine between 1ppm-3ppm. We recommend you stay out of your pool until your free chlorine drops below 5ppm.
If you have extremely high chlorine they sell products that contain sodium thiosulfate to remove the chlorine from your water. Follow the product instructions carefully there is a chance you can remove all the chlorine from your pool and have some left over. Sodium thiosulfate is relatively reactive and should not require a partial drain and fill if you add too much. It will eventaully get used up so long as you dont over do it to the extreme.
It is critical to look at the dosing methods you are using to find out how the level got so high. If you are using a chlorine generator you may want to consider turning down the settings.
If you are using trichlor tablets it is recommended you test for cyauranic acid (CYA). CYA is used to reduce the ultraviolet light degredation of chlorine. At higher levels of CYA, chlorine is less effective as a disinfecting agent.
Consider doing a partial drain and refill to reduce CYA (cyuranic acid stabilizer) if you have a reading over 100 ppm. One hundred parts per million of CYA is quite high. Trichlor raises your CYA levels, which will remain in your pool through evaporation and sunlight. The only way to reduce them is to partially drain and refill your pool. It is necessary during this step to take any precautions, when draining your pool as the chemicals in pool water are toxic to wildlife. Check with your local authorities on the proper way to dispose of pool water.
If you are lacking chlorine you need to address why.
First thing you should do is check on your dosing method and be sure that it is getting to the pool.
If you are using a trichlor feeder make sure that it is getting adequate flow.
Check your chlorinator and varify that it is also producing chlorine. Check the user guide for on your salt system to be sure it is properly maintained. You may be able to call their help line to be sure it is indeed producing the proper ammounts of chlorine for your swimming pool. The cells in these units have a limited lifespan.
Once you verify that you are getting chlorine to the pool, next check your chlorine dosing. You may need to increase it if you are still getting readings lower than one ppm free chlorine. If the dose is inadequate there are two available options to increase your chlorine level.
You can add cyauranic acid to your pool. The suns UV rays deteriorate chlorine I recommend you keep it under 50ppm CYA. CYA makes free chlorine more stable in UV environments, but reduces its disinfecting power significantly. A simple rule of thumb is to limit your CYA to ten times your free chlorine levels or lower. CYA is not necessary, but it will reduce the amount of chlorine lost to the sun. Having CYA in your pool has to potential to reduce the amount of work that your generator has to accomplish to keep up with the clorine loss.