Daytime chlorine loss question

[carlos31820]

I'm on day 7 of my very first SLAM in 5 years. I have a question regarding the large amounts of chlorine loss my pool experiences at these high shock levels during daytime hours. This morning, my FC was 33. When I came home from work (about 12 hours later), the FC was 25.5. However, I just realized that this morning, I had turned on my SWG at 80% and it ran all day today.

It seems like a loss of 7.5ppm even in sunny 92 degree weather seems high - especially with the SWG running all day (I've since turned it off). However, I've never had to SLAM my pool before so I'm not familiar with these high chlorine levels and how the pool behaves.

Does this FC loss seem right?

 

[needsajet]

You can add your city/state/country to your profile which helps understand your conditions. Also the CYA and CC level is helpful, and description of pool before you started and what it looks like now. The FC drop is believable and suggests that your SLAM is working hard to kill algae and eliminate CC. Think about anywhere algae might be hiding (under ladder rungs, behind skimmer weir, inside light niches, etc., etc.). Keep on brushing regularly to break the biofilm protecting the algae. The faster you kill it, the faster the FC loss will slow down. The loss is also high because SLAM level exceeds the capacity of your CYA level to retain the FC. Hence the M in SLAM. The more often you Maintain it, the quicker the SLAM will go.

 

[Texas Splash]

^^ Very true. And remember Carlos, there's two things happening at once .... the higher FC level is getting expended by the abundance of organic material, but at the same time the higher FC is an easier target for the sun's UV. That's why we advise owners to not go over their SLAM level based on that CYA because even at the proper SLAM level, it will drop faster than the FC that has bonded well in an ideal ratio to the CYA. At your normal target level (with no algae) you expect to lose about 2-4 ppm each day. So you can see how losing more than that is very easy to do during a SLAM - especially just the 3.5 ppm more you experienced today. Hope that helps.

 

[bobodaclown]

Just a heads up. Use only 5ml of water then each drop counts as 1ppm. When you SLAM, you don't need the .5 accuracy.

 

[jblizzle]

Just a heads up. Use only 5ml of water then each drop counts as 1ppm. When you SLAM, you don't need the .5 accuracy.

The savings of doing this is quite minimal, just be sure to use 10ml when you go to do the OCLT.

 

[carlos31820]

You can add your city/state/country to your profile which helps understand your conditions. Also the CYA and CC level is helpful, and description of pool before you started and what it looks like now. The FC drop is believable and suggests that your SLAM is working hard to kill algae and eliminate CC. Think about anywhere algae might be hiding (under ladder rungs, behind skimmer weir, inside light niches, etc., etc.). Keep on brushing regularly to break the biofilm protecting the algae. The faster you kill it, the faster the FC loss will slow down. The loss is also high because SLAM level exceeds the capacity of your CYA level to retain the FC. Hence the M in SLAM. The more often you Maintain it, the quicker the SLAM will go.

Thank you for the response. I updated my profile. I live in Midland, Georgia.

The SLAM details can be found in this post...

SLAM questions... (and moral support))