Algaecide Before Or After Shock? (Absolutely the Best Tips for 2024!)

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Do you Add Algaecide Before or After Shock?

You do not need to wait for your pool to go green before you Shock it. In fact, you should Shock your pool every week. Under no circumstances should you wait longer than two weeks. But what about Algaecide? Do you add Algaecide Before Or After Shock?

Algaecide should always be added after Shock. Shock is considered complete only when your pool loses less than 1 ppm of chlorine overnight. Add algaecide only after the chlorine level has dropped to 5 ppm or less. High levels of chlorine make the active ingredients of algaecide ineffective. 

You can add algaecide as usual. You need to, anyhow, check the chlorine level of your pool. It should be between 2 – 4 ppm. The ideal is 3 ppm. Kem-Tek Pool & Spa Concentrated Algaecide is very effective for prevention of algae and also helps to clarify cloudy pool water.

Chlorine level, less than 1 ppm, is a red flag. Get the chlorine level of your pool to 3 ppm first. You can find the amount of chlorine that needs to be added by using an online pool calculator.

I highly recommend using the HTH Super Green to Blue Advanced Shock. It is a 2-part system.

Pack I shocks your pool with a boost of chlorine, helping you fend off bacteria. Pack II is a powerful flocculant that drops particles to the bottom of the pool for easy vacuuming.

Both packs work together to create beautiful, crystal-clear pool water within 24 hours.

Every rule has an exception. The rule “Algaecide After Shock” has an exception too! If rains and storms are forecast before the scheduled pool shock then you should add the algaecide before rains. 

The algaecide will protect from the onslaught of algae, the rainstorm is sure to bring to your pool.

How Long Should you Run your Pool After Adding Algaecide?

Under normal conditions, chlorine level between 2 – 4 ppm is desirable and 3 ppm is ideal.

But shock spikes up the chlorine level to 10 ppm or more. A chlorine level of even 25 ppm, during shock, is not unusual. Shock is basically chlorine on steroids. Shock is what kills all the algae in your pool. 

The role of algaecide to kill algae is secondary. The primary role of algaecide is to prevent growth of algae growth in the next 5 – 7 days after shock. To be effective in this role, the algaecide should be well dissipated throughout the pool.

It is very important to run the pool filter & pump while adding Algaecide. It is best to start the filter pump just before adding Algaecide and let it run for 2-4 hours to ensure adequate circulation.

How Soon After Shock & Algaecide Can You Swim?

You add algaecide after shock, only when the chlorine level has dropped to 5 ppm. This is OK for adding algaecide but still a bit high for swimming. You will get itchy skin and burning eyes.

It is best to wait at least 24 hours after adding the algaecide after shock. 

This is enough time for the algaecide to be fully dissipated and become effective. More importantly the chlorine level would have dropped to below 4 ppm.

In any case, do check the chlorine level before you dive in.

Why is my Pool Still Green After Shock and Algaecide?

You have shocked your pool. The chlorine levels are on target. You have added algaecide. But the pool is still green. In fact it is looking greener than before the shock!

Sounds strange but it can happen. The pool is likely green not because of algae, but because of excessive copper. 

You will know that the green is coming from high copper content if your pool is green but clear. Algae makes your pool water green and murky.

Metals, especially copper, can be present in the water that you use to fill up your pool. As time passes the copper concentration increases. Use of copper algaecides increases the copper content further.

Oxidation occurs as a result of copper’s exposure to air, though water — especially salt water — heat and acidic compounds can also induce corrosion. Oxidation adds a verdigris color (blue-green) to copper or copper carbonates like brass or bronze.

SCIENCING

High copper content in water, use of copper algaecide, high water temperature and low pH can work in conjunction to make even algae free pool water look green.

The short term solution to this problem is:

1. Switch from copper algaecide to polyquat algaecide
2. Use a Metal Sequestering Agent

Jack’s Magic’s The Blue Stuff is a powerful stain remover and is effective at removing copper, iron, and manganese from your pool water. In the longer term you may have to change the source of pool water or pre-filter it for metals.

For more information on Pool Chlorine Types refer to my post Complete Guide To Pool Chlorine Types. (What Is The Best?).

Recommended Swimming Pool Chemicals

Best All Purpose Algaecide

Kem-Tek Pool & Spa Concentrated Algaecide is very effective for prevention of algae and also helps to clarify cloudy pool water. It has a non-foaming formula and can be used in all types of pools.

Best Multi-purpose Pool Shock

The HTH Super Green to Blue Advanced Shock is a 2-part system. Pack I shocks your pool with a boost of chlorine, helping you fend off bacteria. Pack II is a powerful flocculant that drops particles to the bottom of the pool for easy vacuuming. Both packs work together to create beautiful, crystal-clear pool water within 24 hours.

How To Use: Simply follow the on-pack instructions for both Pack I and Pack II. Pack I is the Cal Hypo Shock treatment and Pack II is a flocculant that drops dead particles to the bottom of the pool for easy vacuuming.

Best Sequestering Agent

Jack’s Magic’s The Blue Stuff is a powerful stain remover and is effective at removing copper, iron, and manganese from your pool water. It will work even in high chlorine environments without breaking down. This solution will prevent and remove stains from plaster, vinyl and fiberglass pools safely and quickly.

The Blue Stuff does everything “The Pink Stuff” does and more. “The Blue Stuff”‘s proprietary blend actually removes copper from the water. “The Blue Stuff” is also very stable in higher chlorine levels and can be used in many fountain and water feature applications.

Thank you very much for reading the post. I do hope you found it informative and helpful.