Cloudy water in pools is usually caused by inadequate circulation and filtration, lack of sanitizer, or improper water balance. There are varying degrees of cloudiness from hazy to cloudy. Treating hazy water involves ensuring proper circulation and filtration, adjusting water balance, and using shock or clarifiers. Treating cloudy water requires the same initial steps along with potentially using floccing agents or filter aids to clear the water. Maintaining proper sanitation and water chemistry can prevent cloudy water issues.

1. BIO203: CLOUDY WATER
Pool & Spa University

2. WHAT CAUSES CLOUDY WATER?
➤ Cloudy water is the most common pool problem pool owners
face every year.
➤ There are multiple causes of cloudy water, and they can occur
at the same time:
➤ Inadequate circulation
➤ Inadequate filtration
➤ Lack of sanitizer
➤ Not shocking frequently enough
➤ Improper water balance

3. CLOUDY V. HAZY
➤ Pools can experience varying
degrees of cloudiness,
depending on what is causing
the problem. We use two
terms to define water clarity.
➤ Hazy: the bottom is visible,
but not clearly.
➤ Cloudy: the bottom is not
visible.
➤ It is important to distinguish
how cloudy the pool is, as
recommendations will differ to
fix the issue.

4. CIRCULATION & FILTRATION
➤ Inadequate circulation—usually, not enough circulation—means that not enough
of the pool water is being moved through the filter.
➤ The amount of circulation required is calculated in turnovers, or the amount of
time it takes to move an amount of water through the system equal to the
pool’s total gallonage. However, this does not mean all the water has been circulated
and filtered!
➤ After 5-6 hours of operation, most pools have only circulated roughly 42% of
the total volume; after 10-12 hours, approximately 84% of the volume has been
filtered. At 24 hours, 98% of water has been filtered.
➤ Pool owners should run their pump, at minimum, 10-12 hours a day (24
hours is preferable) in the heat of the day to get the best circulation.
➤ Additionally, the pool should be left uncovered for at least 24 hours over the
course of the week; covered pools have nowhere to release the gases produced
by the pool, leaving those gases to be reabsorbed into the pool and cause
clarity issues as well as other problems.

5. CIRCULATION AND FILTRATION
➤ The filter needs to be in good working order, with fresh media
that is regularly cleaned.
➤ Sand that is older than 5 years or cartridge filters older than
2 years should be replaced.
➤ Sand should be backwashed and cartridge filters cleaned
when pressure increases 8-10psi above “clean pressure,” or
the pressure at which the filter reads after being freshly
cleaned or installed.
➤ Every six weeks (twice a year minimum), the filter(s)
should be chemically cleaned to remove oils, greases, and
other material that regular water will not remove.

6. SANITATION & SHOCK
➤ Low sanitizer levels and not
shocking enough can result in a
buildup of contaminants, making
sanitizer less effective.
➤ Always maintain sanitizer
levels in the recommended
range, preferably at the top of
the range.
➤ Shock weekly, even if the pool
has not been used;
additionally, apply shock after
rainfall, heavy use, and large
water replacements.
➤ Routine oxidation should be a
preventative, not a cure!

7. WATER BALANCE
➤ Multiple parameters can contribute to cloudy water:
➤ High pH on its own will cause dissolved materials to come out of
solution, making the water appear cloudy. High pH will also make
sanitizer and shock less effective, keeping water cloudy longer.
➤ High total hardness (calcium hardness) can result in calcium
falling out of solution, clouding the water.
➤ Excessively high total dissolved solids (TDS) can reduce how
effective chemicals are when added, meaning treatment of cloudy
water takes longer.
➤ The use of off-brand chemicals or non-pool-grade chemicals can
result in unwanted additives entering the pool; in large quantities,
these can cause clouding, especially when added dry to the pool.

8. TREATING HAZY WATER
➤ Ensure the pump is running 24 hours a day and the filter is fresh and has
been recently chemically cleaned.
➤ Check the water balance and adjust out-of-range parameters; for high
calcium, apply BioGuard® Scale Inhibitor to pull calcium back into solution.
➤ Shock the pool if it has not been shocked in the last 48 hours. Sometimes
shock is enough to clear the pool. Be sure to leave the pool uncovered for 8
hours after applying shock.
➤ If shock does not help, a clarifier like Polysheen® Blue or BioGuard®
Natural Clarifier can be used.
➤ Pay close attention to the dosing on Polysheen® Blue; do not overdose!
Excessive clarifier can make a hazy pool worse!
➤ If cleaning up after algae, Pool First Aid™ is a good choice to consume
dead algae along with binding up small particles.

9. TREATING CLOUDY WATER
➤ Ensure the pump is running 24 hours a day and the filter is fresh and has been
recently chemically cleaned.
➤ Check the water balance and adjust out-of-range parameters; for high calcium,
add fresh water to reduce calcium levels or Scale Inhibitor to pull calcium back
into solution.
➤ Shock the pool if it has not been shocked in the last 48 hours. Be sure to leave
the pool uncovered for at least 8 hours after applying shock.
➤ For particularly opaque pools, a floccing agent like PowerFloc™ can help to
settle material to the bottom of the pool to be vacuumed.
➤ PowerFloc cannot be used on pools that do not have an option to vacuum to
waste!
➤ A filter aid like Pool Tonic™ or SoftSwim Filter Aid™ can help to push as much
material into the filter as possible. Pay close attention to filter pressure when
using these products, as it will rise very quickly.

10. WHAT ABOUT…?
➤ Muriatic acid: this can be used to balance the pH to the
recommended range, but habitual use of acid as a “clarifier” to
try to clear a cloudy pool can result in equipment corrosion
and bather discomfort if the pH is too low. Check pH first
before adding muriatic acid.
➤ Stabilizer: excessive stabilizer is not a known contributor to
cloudy water. If stabilizer falls out of solution, it can be
vacuumed.
➤ Bleach: Also known as liquid chlorine, this is a very weak
shock that dissipates very quickly in the pool. Most liquid
chlorine contains fillers that can take time to leave the pool. In
general, there are better options for shock treatments.

11. CONGRATULATIONS!
You have completed the activity!