Sometimes, after adding chlorine to a pool or hot tub, the test strips show no chlorine, but why? Or maybe you're adding chlorine and levels keep dropping?
Cause 1: High chlorine demand
Your pool or hot tub might be experiencing a high chlorine demand. This is due to too many contaminants in the water, and the chlorine is getting used up too quickly. This can happen after periods of heavy use, too many organic contaminants such as body oils, suncream, a build up of bacteria or biofilm, or if the water has been left untreated for a long period of time.
To solve the issue of high chlorine demand:
- Remove any visible debris
- Scrub the internal walls
- Clean / vacuum the floor of the pool/hot tub
- Replace the filter
- Balance TA and pH levels
- Shock dose the water and leave for 24 hours
Cause 2: Unbalanced pH and Total Alkalinity
If Total Alkalinity or pH are not balanced correctly, this could be affecting the chlorine efficiency and result in fluctuation or no chlorine showing. The easy solution is to bring your levels to 7.2 - 7.6 for pH and 80-120ppm for Total Alkalinity, then try adding chlorine again.
Cause 3: TDS (Total Dissolved Solids) is too high
TDS is the total of all dissolved solid matter, such as organic matter, minerals, metals, salts and this includes chemicals too. There will come a point where the water simply cannot take anything more. This usually happens if the water has been in for too long with heavy use and lots of chemical treatment. The only solution is to drain and refill.
Cause 4: Incorrect or old test strips
We will always recommend ClearWater® test strips to gauge the chemical levels in pool or hot tub water, as they have been extensively tested and designed to give accurate readings. You'll need to consider whether you bought genuine test strips from a proper vendor online, or if your test strips are old or have maybe been compromised by allowing moisture into the container.
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