SLAMming Questions - Am I doing it right, how long does it take?

[Junta]

Hi Everyone,

I am having an algae problem in our pool. It wasn't real bad but there was noticeable green on the bottom of the pool. On Monday I started SLAMming my pool. Three days later and I am seeing inconsistent results. One morning my FC will have dropped 1.5 ppm, the next 3 ppm. How long does this normally take? Am I doing something wrong? I have been checking the chlorine level 3-4 times a day. I do it before I leave for work, have my wife check and chlorine as necessary around noon time, then I check when I get home from work (when I brush and vacuum) and finally check later in the evening before I go to bed. Do I need to be doing more frequent checks and addition of chlorine during the day? On another thread, I read that the CYA test from my TF-100 test kit is only accurate to about 10 ppm. My last few CYA tests have me around 45-50 ppm. Could it be that I am not getting my FC up to shock level if my CYA could in fact be closer to 60 rather than 50? I have been trying to keep my FC at 20 ppm. Below are my FC levels since I began this process:

8/31: 6:30 PM-24.5, 10:20 PM-25.5
9/1: 6:30 AM-19.0, 12:30 PM-17.0, 5:00 PM-19.5, 6:50 PM-21.5, 10:00 PM-22.0
9/2: 6:15 AM-20.5, 1:35 PM-16.0, 4:50 PM-22.0, 9:05 PM-19.5, 10:15 PM-23.0
9/3: 6:25 AM-20.0, 10:25 AM-17.0

CC has been 1.0 or below the whole time. Here in CT it has been quite hot the last few days and my pool gets full sun from around 10:30 AM - 2:30 PM. The rest of the time it is shaded with about an hour of filtered sunlight for maybe an hour in the afternoon. Pool temperature is around 80 degrees. Yesterday afternoon I replaced the DE in my filter.

One side question...I have been using the pool calculator to make adjustments to my FC levels. However, my FC level during this process has always come in higher than what the pool calculator says it should. For example if I add bleach to raise my FC from say 17 to 20, when I check my FC after a couple of hours it would be 23. My pool size/volume is set correct. Can anyone shed any light on why this is happening?

Thanks for the help!

Jim

 

[Texas Splash]

Jim, the fact that you have help at home while you're away is great! . You're not doing anything wrong, it just takes time. Keep that FC up at the SLAM level and it WILL work. It may take a week, maybe longer. All depends upon how much algae was in your pool and how consistent you are at maintaining the SLAM. For CYA, round it up or down like with taxes. If it seems to be 55, call it 60, etc. Then adjust FC from there and you'll be fine.
As for the calculator, sometimes we're told the pool is X-gallons, but find that after adding amounts per the calculator it under or over-shoot our target. That may indicate your pool volume is actually different than first thought. You can try adjusting your pool gallons up or down and that may help you pinpoint the true size of your pool better. Keep-up the great work Jim! You and your wife are doing well.

 

[pabeader]

On the side question, two possibilities, either the % is higher then you think or your actual water level is less then 48".
At 4ft. you get 17100 at 3.5 ft you get 15000

 

[run53]

I always have trouble reading CYA accurately, so I overshoot the SLAM FC level. In your case, I would probably SLAM to FC=24, just to be sure (in case your CYA is indeed 60)

 

[Junta]

It took 9 days for my SLAMing process to complete. I did overshoot the SLAM FC level as run53 suggested. I don't know for sure if that helped or not but I think it did. Thanks everyone for the help.