# Thread: Slamming with zero cya

1. ## Slamming with zero cya

Short story.
Lowered chloring to to AA to eliminate iron staining, I have done this successfully in the past thanks to this forum. Followed directions to the T. Now several weeks later and tons of rain, chlorine fell to 0 and would not hold even after adding bleach according to Pool Math calculations. Water is now cloudy but no signs of algae, though that is what I think is happening. Added bleach, CYA in sock in skimmer. I need to SLAM and not sure of how high to go with CYA testing at 0, but my husband just put a full jug into sock in the skimmer.

In order to SLAM what should I take the chlorine level to?

FC 0
TC 0
CC 0

ph 7.6
TA 80
CA 350
CYA 0
CSI -0.18 Balanced

2. ## Re: Slamming with zero cya

I just checked pool math calculator. He added a 4 lb. jug of stabilizer which should raise CYA to 24 but that will take at least several days to dissolve and to be effective.

I don't think that will change the the amount of chlorine I need. The CYA Chlorine chart does not go down to 0 or 24. So I am still wondering what the chlorine should be to slam.

3. ## Re: Slamming with zero cya

Target a CYA of 30ppm. So let that sock dissolve and just assume you're at 30.

In the future, the shock level for zero CYA is 10ppm although people rarely have zero.

Any other value of CYA, the shock level is 40% FC/CYA ratio. So a CYA OF 24ppm would technically be 9.6ppm (round up to 10ppm).

4. ## Re: Slamming with zero cya

If you can occasionally squeeze the sock it will help it desolve much faster. Once it is disssolved, you can consider it all in, and should show up in the test after a good few hours of further mixing. I usually check the day after it is all dissolved.

Shock level is 40% of CYA, so for 25ppm CYA SLAM at FC of 10 until you confirm CYA.

5. ## Re: Slamming with zero cya

To both of you,
Thanks so much. Its pouring again here in Houston, so I will wait a bit to go work on the sock full of stabilizer. Aiming for 10 FC.
Chris

6. ## Re: Slamming with zero cya

Just so you know, the test does not read below 30ppm well. Most people really can't get a good read at 20ppm and, chemically speaking, 20ppm is the solubility limit for the test. So, you could easily have 20ppm CYA, not be able to see that and then add 30ppm by sock only to wind up at 50ppm.

For a SLAM, 30ppm is really optimal as it gives you the UV protection you need but keeps the shock level of chlorine needed at reasonable cost levels and saves on test reagents. Once you get near 50ppm or above, a SLAM really starts to cost \$\$ in terms of bleach needed and reagent usage.

So I would pull the sock at some point and retest CYA to see where you are at.

7. ## Re: Slamming with zero cya

Hi All,
I did as suggested and helped the sock of CYA dissolve yesterday afternoon. Today the CYA level is at 30, actually just a smidgen over halfway between 20 and 30. I really think the pool was at 0. We have had so much rain here in Houston over the winter months, our pool is constantly overflowing the overflow and over the edge at times. I adjusted the chlorine by adding bleach and now the chlorine is at 13.5, TA 60, and the water is much clearer. I am going to keep the chlorine at 10 and check overnight for loss. I never saw any green or yellow staining just cloudy water. I did the AA treatment several weeks ago and was gradually bringing up the chlorine level. I must have let it too low to long, and helped along by lots of rain water. Obviously, I should have checked more often. Lesson learned. Always the best and brightest group of pool people on the internet right here at troublefreepool.com.
Much appreciated,
Chris

8. ## Re: Slamming with zero cya

Hi, Chris,

Be sure to brush your pool during your SLAM to get any small debris up into the chlorinated water to be sucked into the skimmers and filtered out

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