Last Updated: June 19, 2022

Pool Is Still Green After Shocking

Written By: Pool Care Guide

It's not uncommon for pool owners to see their swimming pools remain green even after shocking them. But what could be the cause?

The primary reason your pool is still green after shocking is the presence of metals. Metals like copper and iron oxidize upon exposure to high chlorine concentrations. The green chlorides formed alter your pool's color.

Metals aren't the only reason your pool is green after shocking. Read on and learn more possible reasons.

There Could Be Algae

The existence of algae will make your pool green. Algae thrive in environments filled with sunshine, carbon dioxide, and water. Unfortunately, pools have these essentials, making them ideal habitats for algae.

Even though these organisms are not harmful, they may contain harmful bacteria like salmonella that feed on them. Therefore, swimming in a pool with algae isn't a good choice as you may develop skin irritation.

Why would algae remain in your pool after shocking and adding an algaecide? Possible reasons are poor water circulation and insufficient levels of chlorine. You also need to check on the filtration system and pH balancing.

The Pool's Water May Contain Pollen

It may not have been the algae but high levels of pollen in your pool, especially during the pollen season. The culprits include weed pollen, plant pollen, and grass pollen.

High levels of pollen in the water could result in a green pool. Thankfully, pollen floats on water, making it easier to visualize and remove. So, after shocking your pool and it remains green, look to see if there's pollen floating around.

You can quickly remove pollen by skimming, brushing, and filtering the pool regularly during the pollen season. Remember to clean and maintain your backyard well to reduce pollen levels.

You Have Copper in Your Pool

Did your pool suddenly turn green after shocking? Maybe there is copper metal in the water you used to fill the pool.

During shocking, chlorine and copper react through oxidation, forming a blue to a green product. The pool's final green color is the result of the chlorine copper reaction.

You may need to add a pool metal remover to solve this issue. A good pool metal remover will eliminate heavy metals in your pool, including copper, calcium, and iron, leaving it clean and clear.

Check on Your Filtration System

Are you sure you are using a suitable filtration system for your pool? After shocking, your pool may still be green due to filtration issues, specifically brought about by filter choice.

The three most common pool filters are:

  • Sand filters
  • Diatomaceous Earth filters (D.E)
  • Cartridge filters

Any of these three filters should clean your pool effectively. However, if the pool remains green after shocking, there must be a problem somewhere with your pool filter.

Among the three, sand filters are the easiest to install and use, but you need to backwash them and change them regularly for optimal results. Those using a sand filter must exercise patience because it may take up to seven or more days for the pool to finally clear. But only if you're sure your sand filter is in good shape.

If your filtration system has a D.E filter and after shocking your pool, it remains green, there could be three possible issues to do with the filter. You're not running the pump long enough, you've not been backwashing the D.E filter, or it's defective hence not working as it should.

Finally, you may be using a worn-out cartridge filter, so it's not working well enough. Ensure you change the cartridge filter regularly since it doesn't require backwashing, and run it daily until the pool water clears.

Perhaps You Didn't Brush or Vacuum the Pool Properly

You need to thoroughly brush the walls of your pool to clear all the debris inside. If not well done, even after removing pollen, copper, and algae, the pool will stay green after shocking.

The circulation system may not reach all the pool parts, creating some dead spots that encourage debris to grow. Ensure you have the correct pool brush as per the pool's finishing.

You may need to vacuum the pool after brushing to remove stubborn debris.

Did You Use a Clarifier or Flocculant?

If the pool is still green after shocking, it could be that you didn't use a clarifier or a flocculant. Adding a clarifier or a flocculant will quickly clear the pool, enabling you to see its bottom.

Small particles in the pool could still make it appear cloudy and green even after shocking. Flocculants and clarifiers merge small impurities, making them easy to remove.

The only difference is that a clarifier makes the clump float while a flocculant makes the clump fall to the pool's bottom.

Afterward, skimming, filtration, and vacuuming can quickly remove all the particles, clearing your pool.

You Didn't Shock the Pool the Right Way

You need free chlorine, correct alkalinity levels, and correct pH for your pool to stay clear. So, if your pool is green after shocking, perhaps you didn't balance the chemicals as required or shock it the right way.

Before starting the shocking process, remove all the debris using a leaf net.

The next step is testing the pool's pH levels to determine whether to add more chemicals when shocking. An ideal pH level in a pool should be between 7.2 and 7.8. Proceed to shock the pool when the pH levels are correct.

Disburse liquid chlorine evenly around the pool, then turn on the filter. Allow the process to continue for several hours before brushing the pool thoroughly.

At this point, add an algaecide to prevent algae from growing back after shocking. Let the filter run for a few days until the pool clears.

Final Thoughts

Several reasons could make your pool stay green even after shocking. The most common causes are the presence of copper and algae in the water. The pool water can quickly turn clear with correct chemical balancing, the right filtration system, and proper shock treatment.

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