# Thread: Amount of Bleach consumed to kill Algae at 80 CYA vs. amount used at 30 CYA

1. ## Amount of Bleach consumed to kill Algae at 80 CYA vs. amount used at 30 CYA

Didn't want to steal a thread so I am pasting a comment here to discuss it.

The OP's CYA was 80. Slam level was like 31. The comment was "It would be good to also drain off some water to dilute that CYA level down to something more reasonable in the 30-50 range before you SLAM so it's financially more reasonable in the amount of bleach you'll use."

Let me see if I can state my question intelligibly. Yes, the poster will have to pour more gallons of bleach in to get to slam level than if CYA was 30, but overall it will take the same amount of bleach to kill the algae. X amount of Algae will consume Y amount of CL as it is killed, right? The initial amount poured in may be higher but the residual amount after all the Algae is killed will also be higher.

If not, I don't understand where the CL is going

2. ## Re: Amount of Bleach consumed to kill Algae at 80 CYA vs. amount used at 30 CYA

I plan to keep reminding us all of this until we all die......chlorine is consumed by two things in your pool.........UV from the sun and organics in your pool water.

When you introduce Cl in your pool, it is a percentage of that Cl that gets consumed......not specific volume.

3. ## Re: Amount of Bleach consumed to kill Algae at 80 CYA vs. amount used at 30 CYA

OK, one last time, I can see based on what you say that CL consumed by UV is a percentage. The more CL there is the more UV can consume. But is the amount consumed by algae a percentage? Whereas it is UV consuming the CL it is CL consuming the algae and that seems like it would be a specific amount ( there is a specific amount of algae to consume). But the UV percentage thing explains the benefit of lower CYA.

4. ## Re: Amount of Bleach consumed to kill Algae at 80 CYA vs. amount used at 30 CYA

I think you are right in that you will need Y amount of FC to kill X amount of algae. So, besides the extra FC required to raise up to the higher SLAM level, the amount of FC required to kill the algae should be very similar.

The disadvantages of the SLAM at higher CYA levels are higher loses to the sun (in terms of ppm of FC) and the testing requiring more drops of reagent as well.

5. ## Re: Amount of Bleach consumed to kill Algae at 80 CYA vs. amount used at 30 CYA

Originally Posted by jblizzle
I think you are right in that you will need Y amount of FC to kill X amount of algae. So, besides the extra FC required to raise up to the higher SLAM level, the amount of FC required to kill the algae should be very similar.

The disadvantages of the SLAM at higher CYA levels are higher loses to the sun (in terms of ppm of FC) and the testing requiring more drops of reagent as well.
This makes sense to me'

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