Rob is a pool-service industry professional with over 20 years of experience.
Floc for Pool
I recently received a service call for a green pool cleaning. The state of the pool when I first arrived is pictured above. Below is a step-by-step explanation of how to turn your pool from green to blue.
Step 1: Test the pH
When I tested the water, the P.H. was around 7.2. That is a little low for pool water but perfect for adding shock.
Step 2: Add Granular Chlorine or "Shock"
Because this particular pool was a bit larger than most residential pools, I added approximately seven pounds of granular chlorine, also known as calcium hypo-chloride or shock. Within five minutes, the water began to lose its green coloring and turn blue again.
Step 3: Add the Flocculant
Flocculation is when a chemical, or flocking agent, is added to the green pool water. The solution causes algae particles to bind together and sink to the bottom of the pool. After the particles sink, they can be vacuumed.
Step 4: Clean the Filter
The next step is to ensure the filter is clean since the pump will need to run for 24 hours. With a D.E. filter, you will need to backwash.
Step 5: Let the Pump Run
Letting the pump run will help flush out all of the remaining green water.
Step 6: Add Four Scoops of D.E. Powder
Add four scoops of D.E. powder to coat the filter grids. This is added directly through the skimmer while the pump is running.
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Step 7: Set the Timer
Now the timer needs to be set to run continuously until the next day. Remove the "off" trip lever to allow the pump to run until it is manually shut off.
Step 8: Vacuum the Remaining Residue
After being treated for 24 hours, the pool should have become clear. There may some stubborn areas, especially on the walls. On the bottom of the pool, there may be dead algae and some leftover shock dust. This needs to be vacuumed. You can only vacuum these particles if a D.E. filter is being used; otherwise, it needs to be vacuumed to waste.
Step 9: Backwash the Filter
After the pool has been vacuumed, backwash the filter again.
Step 10: Scrub Remaining Residue With a Brush
You should brush the green areas that can't be reached by the vacuum, such as the tiles, steps, etc.
Step 11: Check the Chemical Balance
Chemicals should be well balanced. The chlorine level may be slightly elevated.
Step 12: Enjoy!
The finished result should be a clear, bright blue pool.
This article is accurate and true to the best of the author’s knowledge. Content is for informational or entertainment purposes only and does not substitute for personal counsel or professional advice in business, financial, legal, or technical matters.
Questions & Answers
Question: I was always told to add shock to the pool before noon when the sun is shining. It’s overcast right now; can I still do the Green to Clean now?
Answer: Shock can be added at any time. Especially since you are treating a green pool. The hot sun can tend to burn off chlorine faster, but the green pool needs to be treated and the sooner, the better. The chlorine will remain high for a few days after shocking anyway whether or not the sun is out.
Sarah Carlsley from Minnesota on June 12, 2012:
Looks like you got it all figured out here when it comes to pools! Nice hub!