Liquid Chlorine for Pool Winterizing in Austin, TX

Do I Need to Winterize My Pool with Liquid Chlorine in Austin, Texas?

In Texas, there is little need to Winterize a pool as temperatures do not get low enough for long enough to warrant this. There are, however, some steps that YardDoc recommends during the cooler months.

Types of Chlorine


Chlorine Tablets with Stabilizer

The most common form of chlorine added to pools is the regular chlorine tablet. This tablet is generally half chlorine and half Cyanuric Acid, otherwise known as stabilizer.


Without stabilizer, the half-life of chlorine in strong sunlight can be as little as two hours. That means after two hours the chlorine added would have been reduced by 50%. After four hours only 25% would remain. Without adding chlorine continuously this wouldn’t work. To mitigate the effects of sunlight, stabilizer is added to the water, protecting the chlorine.

The Problem with Stabilizer

The problem with stabilizer is that it never evaporates out. It progressively builds up in the water and ultimately gets to a level where it creates chlorine block, eventually making chlorine ineffective. The only way to get rid of stabilizer is to:

  • Extract it via reverse osmosis, which is pricey, or
  • Drain, or partially drain, the pool and add fresh water.


Liquid Chlorine to Winterize a Pool

During the cooler months there is a lot less going on in pools and the chlorine demand is lower. Additionally, the effects of the sun on chlorine are less so chlorine without stabilizer can be used. This is where liquid chlorine plays a role. YardDoc switches to liquid chlorine as soon as the average water temperature drops below 62 degrees.


Liquid chlorine does not contain any stabilizer. This means that during the cooler months your inground pool is still maintained and perfectly usable but stabilizer is not being added to the water. This helps reduce the build-up of stabilizer over time.


In the cooler months, algae activity reduces considerably as algae rely on sunlight for photosynthesis. There is simply less sunlight and therefore less algae. The result is that pool filtration run times can be reduced to around 60% of that required in Summer. Additionally, chlorine levels can be reduced, as low as 1 or 2 parts per million (Summer would typically be 4 to 6 parts per million).


Granular Chlorine - Calcium Buildup

CalHypo is the most common granular chlorine used. It has the issue of adding calcium to the water which also builds up over time. The calcium does not evaporate and can only be reduced by reverse osmosis or replacing the water.


As the need for chlorine is less in Winter, it follows that shocking is generally not needed to the same degree as in the hotter months. Liquid chlorine can take over this role but without the added calcium.

Check Your Freeze Guard

To winterize a pool, YardDoc recommends checking that the freeze guard on your inground pool system is functional. A freeze guard is a temperature sensor – electronic or mechanical – that activates the system when a set temperature is reached.


Typically a temperature of below 38 to 43 degrees will activate the freeze guard. Once activated the freeze guard keeps all systems running in order to reduce the risk of water freezing in pipes or equipment that could cause damage.


YardDoc can assist with a freeze guard check. If all systems start up automatically when the temperature is close to freezing, then you probably have a freeze guard that is working as designed and there is no need for a check. Just be sure that all systems (except the heaters) come on while under freeze protect mode.

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