How early can I test for an Overnight Chlorine Loss Test?

frankytii

Active member
Jun 8, 2019
38
Boston, MA
I am currently performing a SLAM and believe I may almost be done. I tested my FC at 10:30pm. How early in the morning can I test my FC to complete the Chlorine Loss Test?
 

frankytii

Active member
Jun 8, 2019
38
Boston, MA
I suggest you slam for an extra day to be certain you're done and then do the OCLT along with all 3 criteria.
Failed the OCLT. Water has been crystal clear and has a CC of 0.5ppm, but I lost 3ppm of FC during the OCLT. I’ll be going on day 11 of the SLAM. Started because I had a CC of 1.5ppm. I’ve been brushing and vacuuming every day too. Filter pressure has been good. Is there a need to backwash during a SLAM if the filter pressure hasn’t increased?
 

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mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,528
Laughlin, NV
Backwash your filter when your filter pressure rises by 25% over clean filter pressure.

Stay at the SLAM. Check all possible hiding places for algae, Light niche, skimmer throat, weir door, etc.
 

frankytii

Active member
Jun 8, 2019
38
Boston, MA
Backwash your filter when your filter pressure rises by 25% over clean filter pressure.

Stay at the SLAM. Check all possible hiding places for algae, Light niche, skimmer throat, weir door, etc.
Will do. Should I unscrew the light and clean behind it? I’ve never removed it before.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,528
Laughlin, NV
Does your light have a metal ring around it? If so, check for a single screw near the top. Remove that screw, the ring should swing down, and the light assembly brought to the surface on the deck. Then clean the niche. Be ready -----
 

frankytii

Active member
Jun 8, 2019
38
Boston, MA
Does your light have a metal ring around it? If so, check for a single screw near the top. Remove that screw, the ring should swing down, and the light assembly brought to the surface on the deck. Then clean the niche. Be ready -----
It has a white plastic ring with a single screw on top. I’ll do that. Is it likely to be pretty nasty behind there?
 

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Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,915
San Dimas, CA (LA County)
Failed the OCLT. Water has been crystal clear and has a CC of 0.5ppm, but I lost 3ppm of FC during the OCLT. I’ll be going on day 11 of the SLAM. Started because I had a CC of 1.5ppm. I’ve been brushing and vacuuming every day too. Filter pressure has been good. Is there a need to backwash during a SLAM if the filter pressure hasn’t increased?
The answer is maybe and that's final. The light is a good place to start.


Then there's the skimmer

And I can't find the thread, but within the last couple weeks someone struggled with finishing a slam on a crystal clear pool and it was some kind of slime on his cartridge filter. A good cleaning and he passed.
 

frankytii

Active member
Jun 8, 2019
38
Boston, MA
The answer is maybe and that's final. The light is a good place to start.


Then there's the skimmer

And I can't find the thread, but within the last couple weeks someone struggled with finishing a slam on a crystal clear pool and it was some kind of slime on his cartridge filter. A good cleaning and he passed.
Thank you. The photos from that light niche thread were shocking. I’ll start there. I’ve scrubbed the inside of skimmer already and I don’t have a weir door.
 

mgtfp

Bronze Supporter
Mar 5, 2020
390
Melbourne, Australia
Another place where I once found algae is in the connections of the individual segments of the pool hose. If you have a suction side cleaner that is permanently in the water and the hose is not fully submerged, then algae can get a hold in there. If you have one of those segmented hoses, then it's worth taking that apart, and give the connections a good brush and soak in your SLAM level water.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,528
Laughlin, NV
Hard to say. May be done tonight. Leave the light out of the niche over night. Also, if you can hang the light into the water so it is fully immersed in the SLAM level FC water too.