SLAM questions

[CarolD]

Hi TFP gurus! I am mid-SLAM and I have questions!
1. Vacuuming to waste. Several posts I've read said to vacuum to waste to get rid of the dead algae and other debris. My vacuum is integrated to the pool and runs into the filter. If I *can* vacuum to waste, I don't know how. I usually just leave my vacuum in the pool all the time, and it runs when the pump is on high or medium. Then I clean out the filter basket at the pump weekly or more often if needed. Is there something different I should be doing here?
2. Related: I see people talk about needing to backwash the filter in the midst of a SLAM. Since I have a cartridge filter, I don't backwash. My pressure is not climbing...do I need to break down the filter and clean the cartridges during or after the SLAM?
3. This is really more of a chem geek question. I looked in that forum area and couldn't find the answer but I'm sure this has been answered before. What is the science behind the shock level of chlorine during a SLAM? I see that SLAM level of FC is about 40% of CYA, but I am wondering why. For this SLAM, I am reading my CYA at 60. If I misread my CYA test, and my CYA is really 70, then I am short on chlorine. Will the SLAM still work, and just take longer? How did the level of 40% get settled on?

Thanks so much for the help. I've included a couple of pictures of my pool...it's very clear, but I lost 3.5 FC overnight, so I know I'm not done yet.

 

[ajw22]

Hi TFP gurus! I am mid-SLAM and I have questions!
1. Vacuuming to waste. Several posts I've read said to vacuum to waste to get rid of the dead algae and other debris. My vacuum is integrated to the pool and runs into the filter. If I *can* vacuum to waste, I don't know how. I usually just leave my vacuum in the pool all the time, and it runs when the pump is on high or medium. Then I clean out the filter basket at the pump weekly or more often if needed. Is there something different I should be doing here?

Your pool setup with a cartridge filter and cleaner does not allow you to vacuum to waste. There are lots of different pool setups.

2. Related: I see people talk about needing to backwash the filter in the midst of a SLAM. Since I have a cartridge filter, I don't backwash. My pressure is not climbing...do I need to break down the filter and clean the cartridges during or after the SLAM?

You vacuum into your cartridge filter. Monitor your filter pressure and clean it when it gets 25% over clean pressure. You have the benefit of a very large cartridge filter which can go a long time between cleanings. You may want to clean your filter after the SLAM Process is complete.

3. This is really more of a chem geek question. I looked in that forum area and couldn't find the answer but I'm sure this has been answered before. What is the science behind the shock level of chlorine during a SLAM? I see that SLAM level of FC is about 40% of CYA, but I am wondering why. For this SLAM, I am reading my CYA at 60. If I misread my CYA test, and my CYA is really 70, then I am short on chlorine. Will the SLAM still work, and just take longer? How did the level of 40% get settled on?

The SLAM FC level balances different factors. You want enough chlorine so the kill rate of the chlorine is greater then the replication rate of algae. You want the level to be low enough to be safe to swim in. You want it to be not damage liners or bleach any color.

The bottom of the FC/CYA Levels contains this acknowledgement:

Acknowledgment: The original Chlorine/CYA “Best Guess” chart was developed by Ben Powell. Richard Falk (chem geek) has refined and expanded on that original to produce the Chlorine/CYA Chart by Chem Geek based on experiences with members on this forum and the old Pool Forum and conformation to chemical theory.

 

[CarolD]

Thanks for the info! I have been watching the pool and adjusting chlorine every 2-4 hours (I had to leave for an appointment...thus the four hour gap). I noticed that I am burning chlorine like crazy...way more than before I started the SLAM process yesterday. Over the past few days, I have been losing about 3-4 ppm per day. Today, I lost 8 ppm just in the last four hours! Assuming I had all this algae in the pool over the past few days, why was I not burning more chlorine, and is it normal to lose so much chlorine all in one short period during the SLAM?

 

[ajw22]

The chlorine is doing it's job. You would not be losing the chlorine if there were not organics in the pool to consume it. THE SLAM is a process and it takes time and patience to kill more algae then it is replicating.

 

[Mdragger88]

Keep at it! You have a beautiful pool! Be sure and run your water features & check all light niches, ladders, drain cover etc. for algae. Also brush, brush, brush! You may have algae hiding somewhere...