Based on personal experience, I would like to suggest two additions to the instructions for SLAMing a pool.
(Note - My water was clear - THANK YOU borates - but a newly installed Liquidator couldn't build up any level of Free Chlorine. Something was eating the chlorine.)
1) Recommend that SLAMmers open up and clean out light niches and any other places where water doesn't readily circulate.
In this thread (low-fc-can-t-figure-out-why-t66420.html), alphadog had been SLAMing his pool for 4 days without any noticeable improvement in chlorine demand. Butterfly suggested "checking out" his light niche. Techguy commented "Light niches seem to be the number one cause of long term failures of OCLT. Clean out the niche, bump your FC." As soon as alphadog opened and cleaned out his light niche, he was able to hold the SLAM chlorine level.
I had the same experience. After unsuccessfully SLAMing my pool for several days I discovered the thread referenced above. As soon as I opened the light niche and cleaned the mung out, and exposed the niche to the high FC in the pool water, I was able to successfully complete the SLAM process and use the Liquidator.
Notes - Rather than go into the pool, with its high FC, I used a toilet brush to clean out the niche. Under the heading of "can't hurt, might help" I used a funnel and a short length of garden hose to pour several gallons of bleach directly into the niche. I also poured bleach directly over the back of the light fixture.
2) SLAMing a pool may remove metal sequestrants from the water, possibly causing staining. The sequestrant level may have to be reestablished after SLAMing. It might also be best to perform a stain treatment after SLAMing a pool, rather than before.
I learned from Jack's Magic that their Blue Stuff can withstand around 10 PPM of FC for a short period, but higher FC levels, or longer periods of time, will "consume" the sequestrant. After SLAMing, the sequestrant level may have to be built back up.
Just prior to SLAMing my pool I had performed an AA stain treatment. After the AA treatment I put in 2 quarts of Blue Stuff. (this was the first time I had used Blue Stuff. The recommended amount was 1.5 quarts for my 15,000 gallon pool.) After I completed the SLAM, the metal stains started to reappear.
As part of starting to use Blue Stuff (but after the SLAM), I purchased a sequestrant test kit from LaMotte (after confirming that it would work with the sequestrant in Blue Stuff). The recommended level of sequestrant is 10-12 ppm. Despite having added (so far) 4 quarts of post-SLAM Blue Stuff, I've never been able to get above 4-5 ppm. The tech at Jack's Magic confirmed that the high FC levels of the SLAM probably "consumed" the (old and new) sequestrant, liberating the metals which were then re-deposited. He said that I wouldn't be able to get up to the 10-12 ppm level until all the now-free metals were bound up and a residual level of sequestrant could be built up. He said that this could easily take several more quarts of Blue Stuff. (I apparently have *lots* of metal in my water, and the nominal 1.5 quart recommendation, with weekly 1/4-1/3 quart additions, might have been insufficient.)
(Note - My water was clear - THANK YOU borates - but a newly installed Liquidator couldn't build up any level of Free Chlorine. Something was eating the chlorine.)
1) Recommend that SLAMmers open up and clean out light niches and any other places where water doesn't readily circulate.
In this thread (low-fc-can-t-figure-out-why-t66420.html), alphadog had been SLAMing his pool for 4 days without any noticeable improvement in chlorine demand. Butterfly suggested "checking out" his light niche. Techguy commented "Light niches seem to be the number one cause of long term failures of OCLT. Clean out the niche, bump your FC." As soon as alphadog opened and cleaned out his light niche, he was able to hold the SLAM chlorine level.
I had the same experience. After unsuccessfully SLAMing my pool for several days I discovered the thread referenced above. As soon as I opened the light niche and cleaned the mung out, and exposed the niche to the high FC in the pool water, I was able to successfully complete the SLAM process and use the Liquidator.
Notes - Rather than go into the pool, with its high FC, I used a toilet brush to clean out the niche. Under the heading of "can't hurt, might help" I used a funnel and a short length of garden hose to pour several gallons of bleach directly into the niche. I also poured bleach directly over the back of the light fixture.
2) SLAMing a pool may remove metal sequestrants from the water, possibly causing staining. The sequestrant level may have to be reestablished after SLAMing. It might also be best to perform a stain treatment after SLAMing a pool, rather than before.
I learned from Jack's Magic that their Blue Stuff can withstand around 10 PPM of FC for a short period, but higher FC levels, or longer periods of time, will "consume" the sequestrant. After SLAMing, the sequestrant level may have to be built back up.
Just prior to SLAMing my pool I had performed an AA stain treatment. After the AA treatment I put in 2 quarts of Blue Stuff. (this was the first time I had used Blue Stuff. The recommended amount was 1.5 quarts for my 15,000 gallon pool.) After I completed the SLAM, the metal stains started to reappear.
As part of starting to use Blue Stuff (but after the SLAM), I purchased a sequestrant test kit from LaMotte (after confirming that it would work with the sequestrant in Blue Stuff). The recommended level of sequestrant is 10-12 ppm. Despite having added (so far) 4 quarts of post-SLAM Blue Stuff, I've never been able to get above 4-5 ppm. The tech at Jack's Magic confirmed that the high FC levels of the SLAM probably "consumed" the (old and new) sequestrant, liberating the metals which were then re-deposited. He said that I wouldn't be able to get up to the 10-12 ppm level until all the now-free metals were bound up and a residual level of sequestrant could be built up. He said that this could easily take several more quarts of Blue Stuff. (I apparently have *lots* of metal in my water, and the nominal 1.5 quart recommendation, with weekly 1/4-1/3 quart additions, might have been insufficient.)