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Using Aluminum Sulphate (Floc) to Lower the CYA Level in Your Pool with Rudy Stankowitz

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Added by shubnigg in Outdoors equipments


Rudy Stankowitz besides being a CPO instructor and a Pool Industry Insider is known as a myth buster in the industry. If you listen to the other podcasts in this series he will speak on if you can lower the pH in your pool without lowering the alkalinity, “Chlorine Lock” and is a Salt Water Pool a Chlorine Pool? In this article, I will focus on the talk we had about lowering the pool’s CYA level with Alum/Floc (Aluminum Sulphate).

To listen to the other parts in this Series:
Part 1 Lowering Your Pool’s CYA Level with Aluminum Sulphate Interview with Rudy Stankowitz:

Part 2 Truth or Myth: "Can you Lower your pH without Lowering Total Alkalinity" with Rudy Stankowitz:

Part 3 Using Borates in your Pool & Acceptable Chemical Levels with Rudy Stankowitz:

Part 4 Truth or Myth: "Chlorine Lock" with Rudy Stankowitz:

Part 5 Truth Or Myth: "A Salt Water Pool is Not a Chlorine Pool" with Rudy Stankowitz:

To learn more about the courses Rudy offers:

00:00 Intro
01:10 About Rudy
02:42 CPO Course
08:00 Rudy's Sites
09:15 Using Alum to Lower CYA

The most common way to lower your CYA level in your pool is by partially or completely draining your pool. You can also try products like Bio-Active but the cost of each bag may be more expensive than actually draining your pool. Rudy has come up with a novel way to lower your pool’s CYA level by half and that is with the use of Aluminum Sulphate (Alum).

The typical use for Alum is when you Floc a pool to turn around a green pool. This clumps everything together and drops it to the bottom of the pool after a 24-48 period. Then you would vacuum out in “Waste” mode if you have a sand filter or D.E. filter with a Multi-Port Valve. If your service account or pool does not have a “Waste” mode you will have to vacuum out the pool bottom with a portable pump. I have a video on my channel that shows how to build one.

How to build a portable clean-up pump

This step is crucial if you want to lower the CYA down using Alum. You do not want to vacuum everything back up into the D.E., Sand, or Cartridge filter. Instead, you want everything that has fallen to the bottom to be vacuumed out to a drain or into the sewer and not back into your pool’s filtration system. No one knows quite why the Alum drops the CYA level in a pool but results using this formula have dropped CYA in half in many cases.

8 lbs. of Alum seems to be the magic number to reduce CYA by 50%.

This is all still a theory, but the results have been documented and are real. So, it appears to work although it hasn’t been verified in a lab or under lab type conditions. But out in the field pool professional have been reporting the effectiveness of this treatment.

If you have never used Alum to Floc a pool the method is very simple. Add the 8 lbs of Alum, run the pool in “Recirculate” mode if possible for 1 hour (you need a Multi-Port Valve for this). If not just add the Alum and go to the next step which is to turn the pool off for 24-48 hours. Everything should fall out and drop to the bottom. Then you would simply vacuum everything off the bottom with the Multi-Port on “Waste” mode or with a portable cleanup pump. If your CYA was at 100 ppm you can check it and it should be around 50 ppm after this process.

Draining is still the most effective way to lower your CYA but this method opens the door up for reducing the CYA in a situation where draining is not an option.

Visit my Website:
YouTube Video Index: – A list of all of my videos.
Join me on Patreon:
Podcast Website:
Coaching Site:
Shop at Leslie's: Leslie’s Pool Supplies has been do-it-yourselfers and pool trade professionals trusted partner since 1963, providing quality products and services to make pool care easy and solutions and expertise to do it right.

#alumlowercya, #Flocandcya, #lowerpoolcya

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