By The Zagosa Team. Published .
Reviewed or updated .
Shock treatment oxidises contamination but does not physically take the resulting material out of your tub. Very small particles can remain suspended and leave the water looking milky. Filter continuously for 24 hours, rinse the cartridge and use the correct dose of clarifier if the haze remains. Most post-shock cloudiness should then improve over the following day or two.
What shocking leaves behind
Shock oxidises algae, organic bather waste and other contamination. The process can leave microscopic debris floating through the water. A typical cartridge captures particles of roughly 20 microns and larger, while finer material can repeatedly pass through its pleats.
This means a new haze after treatment does not automatically mean the shock failed. Oxidation and removal are separate jobs, and filtration must complete the second one.
Steps to remove the cloudiness
- Run filtration without interruption for 24 hours instead of relying on the normal timed cycles.
- Halfway through, remove and rinse the cartridge. A filter loaded with debris has less useful flow and trapping capacity.
- If cloudiness remains, add 50 ml of Sparkle Clarifier per 1,500 L. The polymer gathers fine particles into groups large enough for the cartridge to retain. One treatment is usually enough, but badly affected water may need a second label dose after two or three days.
- Test again. Correct total alkalinity to 80 to 120 ppm, pH to 7.2 to 7.6 and calcium hardness to 150 to 250 ppm. Poor balance can keep minerals suspended and add another source of haze.
When to check another cause
If balanced water is still cloudy after four or five days of continuous filtering and cartridge rinsing, inspect the cartridge closely. A worn element can lose its ability to retain fine particles even when its surface appears clean. Deep-clean it monthly and expect to replace it at about a year, or sooner if the pleats are damaged.
Cloudiness that clears but returns within hours can indicate a heavy deposit in the pipework. At the next water change, use Hot Tub Flush before draining so material hidden behind the jets leaves with the old water.
Post-shock cloudiness questions
Can I bathe in cloudy water?
Wait until the tub is visibly clear and testing confirms free chlorine at 3 to 5 ppm or total bromine at 4 to 6 ppm. If you cannot see the footwell or seats properly, do not use the tub.
Should I add more shock straight away?
No. Consecutive shock treatments can create more material for the filter to collect and may leave sanitiser above its normal range. Filter and clarify first, then retest. Apply another shock only when the readings and product instructions show that it is needed.
Can clarifier replace shock treatment?
No. Shock oxidises contamination, while clarifier helps your filter capture the fine residue. They perform different parts of the clean-up and should be used in that order when both are required.