I've seen many cloudy pools. In water treatment sector, this "cloudiness" means high turbidity, which is a result of poor filtration. Poor filtration basically means that small particles were not captured by the filter.  

But in pools, it's not always the case. Even though the water could be filtered properly, there's a high possibility that the water may still be "cloudy". Why is that?

The no. 1 reason is high pH.

It may not come as a surprise to most of you but there are pool owners who are totally oblivious to the fact that high pH can cause the pool water to become cloudy.

How does High pH make pool cloudy?

High pH is one of the main factors indicated in Langelier Saturation Index (LSI). LSI is used by water treatment companies to measure calcium carbonate saturation of water. LSI indicates whether your pool water is corrosive or scaling. But let's not dive into the science of it. The main point is that High pH pushes the water into scaling range, where white calcium particles start kicking out of the pool water. These floating tiny, white specks give your pool the "cloudy appearance". Another indicator that your water is scaling is if you see the white lines on the pool tiles along the water line.

What's the cause of High pH?

Not going into the science behind this, the main reason why pH rises quickly is due to High Total Alkalinity (TA) , and Aeration of water (Splashing, Water Falls, Water Jets, anything that creates air bubbles in water). Total Alkalinity is also one of the factors in LSI. High TA leads to high pH. 

Water features also raise the pH. That's why pools that have them need pH adjustment almost every day, and other pools requires less frequent pH adjustment.

How often should you check for pH?

My answer is daily, at least for pool owners with water features. Use a test strip, and in 15 seconds, you can know the pool's pH. 

So how to solve high pH problem?

Solve the main causes of it: TA and Aeration. TA should be maintained between 80-100ppm (I maintain mine at 90ppm.) You can use either muriatic or dry acid to lower TA's level. (By the way, TA should be tested using a water test kit - Waterco has one - , instead of test strips. It's more reliable).

As for water features, don't run them when not needed. But if you're using them regularly, then give your pool that extra care it deserves by checking pH daily, and lowering it down with acid. Best part is you can lower both TA and pH using acid. Use this calculator to compute the correct dosage of acid required for pH. No need to overdose.

What if the pH is fine but the pool is still cloudy?

As mentioned in the first paragraph, this happens due to poor filtration. Poorly filtered pools have high organic matter, and very small particles that make it look cloudy and dirty. First option would always be to improve filtration. I use sand filter, but instead of putting sand, I use AFM® Activated Filter Media. If sized properly, it gives a filtration quality of 1 micron without any chemicals required. They are easy to maintain, but a bit bulky when sized properly. If you have small space, use a DE Filter instead. DE filters are a bit hard to maintain, but the water quality is awesome.

But if you don't want to change your filter, then I would suggest using a high quality Clarifier. (I use Clear-Up Pool Clarifier) Clarifiers bind small particles together, effectively making them big in size. (multiple small particles combine, becoming one big particle) These particles can then be either vacuumed or filtered out of the water. If you think your filter needs a helping hand, then clarifier is the way.

Thirdly, use High-Quality Chlorine that dissolves quickly in the pool and does not unnecessarily add more calcium carbonate. High quality chlorine not only saves you money in the long run, but also keeps your pool clear of extra fillers found in cheap chlorine. (Since I have an outdoor pool, I currently use 90% Chlorine from Astral).

Try these actions for yourself and let me know. If this blog helped you, kindly comment below. Thank you for your attention.