SLAM frustrations


Well-known member
Jun 9, 2014
Marietta, GA
I have experience with SLAM's, as I had to do 2 of them last season. This year I let the pool go green over the winter, and started my SLAM on April 15. My numbers for overnight loss are trending down, but my losses during the day are going up. I realize that sunlight will impact the loss during the day, but I am losing an average of 0.20 ppm at night, and an avg of 0.45 ppm during the day. This equates to about 2.0 loss at night, and over 5.0 during the day. Am I correct in my thinking that based on my numbers above, of the loss of 5 during the day, 2 of it is due to the algea, since that is what I lose at night, and the other 3 is due to the sunlight? It is just frustrating because the water has been crystal clear for 2 weeks, yet I have been in the SLAM for 3 weeks and still not able to pass the OCLT.

Also of note, I am not able to check throughout the day, only once at around 7:30 AM, and again around 6.


LifeTime Supporter
TFP Guide
Jan 18, 2015
Bunbury, WA, Australia
I think a good starting point would be to confirm your CYA level again and make sure you are SLAMing at the right level. The key also is to maintain the SLAM level of FC for your CYA level as much as possible.

If you are only dosing in the morning and then at the end of the day (which is the way life goes) it could be that the FC level is spending more time below your SLAM level than not.

If you get an opportunity to test at least another time during the day and redose that would be great. You might also want to consider going just a little higher than your SLAM level when you redose in the morning.


Well-known member
Jun 9, 2014
Marietta, GA
The "sediment" is most likely dead algae.

Can you post a current set of test results, please

pH: 7.5
FC: 13
CC: 0
TA: 60
CH: 90
CYA: 35

I was about to add 180oz 8.25 bleach to bring FC back to 18. I see my shock FC based on pool store CYA test of 45 because I was out of the reagent. Then about 2 weeks into the SLAM, I got a refill and my own test came in at 35. So far I have left the shock target at 18, but it really should be 14.

Sent from my iPhone using Tapatalk


Mod Squad
TFP Expert
Platinum Supporter
LifeTime Supporter
In The Industry
Apr 1, 2007
Sebring, Florida
Yeah, Thanks for those tests! Very helpful. It appears to me that you are doing everything correctly so now you just need some patience. I would keep the FC at 18 as much as possible.

With you DILIGENTLY keeping the chlorine up. I think your SLAM will soon be done. Carefully vacuum that sediment up each day. Getting it out of the pool and into the filter will help.

Once you no longer see that sediment, I would then (and not before then) do another OCLT and see if you pass. You are patient and determined.

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Mr. D

Silver Supporter
May 8, 2016
Huntsville AL
This equates to about 2.0 loss at night, and over 5.0 during the day.

I'm in North Alabama and just finished my opening SLAM and experienced those same numbers. I too could only pull a sample in the Am and than the evening when I returned from work, I would add a little extra bleach in the AM and when I returned in the PM went right into getting it back to SLAM levels. In the end it took me 5 days working it this way to pass my OCLT.

PIA but we got to work.
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