Hi all. I started a SLAM 48+ hours ago because I noticed what I thought was yellow colored algae in various spots around the pool. It doesn't seem to be disappearing and I can't rub it away with my finger with vigorous scrubbing so could these spots be some sort of stain in the plaster? And if so, what causes a yellowish stain like this? Also, these areas are only evident when it is overcast or shady. When the sun is beaming I cannot differentiate these areas from the rest of the plaster (it all looks sparkling blue). I noticed these areas last summer as well but lived with it without attempting a SLAM. Could it be algae living deep in the plaster where brushing and maintaining high FC won't do anything?
Attached a couple pics, but camera doesn't pic up the discolorations very well... so I added arrows.
Also here are my recent log from Pool Math app:
==========================================
Lynds
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Build Type: Plaster
Volume: 17500 gallons
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Latest Test Result Summary:
FC: 18.0 (3 hours ago)
CC: 0.0 (2 days ago)
pH: 7.8 (yesterday)
TA: 70 (26 days ago)
CH: 300 (2 months ago)
CYA: 55 (2 days ago)
TEMPERATURE: 76° (3 hours ago)
CSI: -0.01 (3 hours ago)
==========================================
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Maintenance 04-29-2021 @ 01:35 PM
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Brushed
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Chemical Addition 04-29-2021 @ 01:35 PM
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+ 149 FluidOunces of Bleach
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Test Results 04-29-2021 @ 01:34 PM
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Free Chlorine: 18.0
Temperature: 76°F
CSI: -0.01
------------------------------------------
Notes 04-29-2021 @ 07:31 AM
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Had been adding bleach to get FC to 22 for SLAM. Since FC maintained a good level overnight (21.5), I will bump up to 25.
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Chemical Addition 04-29-2021 @ 07:31 AM
------------------------------------------
+ 96 FluidOunces of Bleach
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Test Results 04-29-2021 @ 07:30 AM
------------------------------------------
Free Chlorine: 20.5
CSI: -0.03
------------------------------------------
Chemical Addition 04-28-2021 @ 08:47 PM
------------------------------------------
+ 96 FluidOunces of Bleach
------------------------------------------
Test Results 04-28-2021 @ 08:47 PM
------------------------------------------
Free Chlorine: 17.5
CSI: -0.03
------------------------------------------
Maintenance 04-28-2021 @ 01:01 PM
------------------------------------------
Brushed
Pressure: 17
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Chemical Addition 04-28-2021 @ 01:01 PM
------------------------------------------
+ 107 FluidOunces of Bleach
------------------------------------------
Test Results 04-28-2021 @ 01:01 PM
------------------------------------------
Free Chlorine: 17.0
Temperature: 75°F
CSI: -0.03
------------------------------------------
Chemical Addition 04-28-2021 @ 07:26 AM
------------------------------------------
+ 96 FluidOunces of Bleach
------------------------------------------
Test Results 04-28-2021 @ 07:24 AM
------------------------------------------
Free Chlorine: 17.5
pH: 7.8
CSI: -0.03
------------------------------------------
Maintenance 04-27-2021 @ 03:58 PM
------------------------------------------
Brushed
Pressure: 17.5
------------------------------------------
Test Results 04-27-2021 @ 03:57 PM
------------------------------------------
Free Chlorine: 21.0
CSI: 0.16
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Notes 04-27-2021 @ 01:23 PM
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Started SLAM with CYA 55. added 308 oz bleach to hopefully bring FC from 7.5 to 22.
Need to maintain FC 22 over next several days.
------------------------------------------
Chemical Addition 04-27-2021 @ 01:21 PM
------------------------------------------
+ 308 FluidOunces of Bleach
------------------------------------------
Chemical Addition 04-27-2021 @ 01:11 PM
------------------------------------------
+ 23 FluidOunces of Baume31
------------------------------------------
Test Results 04-27-2021 @ 01:06 PM
------------------------------------------
Free Chlorine: 7.5
Combined Chlorine: 0.0
pH: 8.0
CYA: 55
CSI: 0.16
------------------------------------------
Maintenance 04-27-2021 @ 01:06 PM
------------------------------------------
Pressure: 17.5
------------------------------------------
Notes 04-27-2021 @ 11:57 AM
------------------------------------------
Noticed yellow algae bloom near steps. Poured 64 oz bleach near steps with pump off. May need to SLAM.
Attached a couple pics, but camera doesn't pic up the discolorations very well... so I added arrows.
Also here are my recent log from Pool Math app:
==========================================
Lynds
------------------------------------------
Build Type: Plaster
Volume: 17500 gallons
------------------------------------------
Latest Test Result Summary:
FC: 18.0 (3 hours ago)
CC: 0.0 (2 days ago)
pH: 7.8 (yesterday)
TA: 70 (26 days ago)
CH: 300 (2 months ago)
CYA: 55 (2 days ago)
TEMPERATURE: 76° (3 hours ago)
CSI: -0.01 (3 hours ago)
==========================================
------------------------------------------
Maintenance 04-29-2021 @ 01:35 PM
------------------------------------------
Brushed
------------------------------------------
Chemical Addition 04-29-2021 @ 01:35 PM
------------------------------------------
+ 149 FluidOunces of Bleach
------------------------------------------
Test Results 04-29-2021 @ 01:34 PM
------------------------------------------
Free Chlorine: 18.0
Temperature: 76°F
CSI: -0.01
------------------------------------------
Notes 04-29-2021 @ 07:31 AM
------------------------------------------
Had been adding bleach to get FC to 22 for SLAM. Since FC maintained a good level overnight (21.5), I will bump up to 25.
------------------------------------------
Chemical Addition 04-29-2021 @ 07:31 AM
------------------------------------------
+ 96 FluidOunces of Bleach
------------------------------------------
Test Results 04-29-2021 @ 07:30 AM
------------------------------------------
Free Chlorine: 20.5
CSI: -0.03
------------------------------------------
Chemical Addition 04-28-2021 @ 08:47 PM
------------------------------------------
+ 96 FluidOunces of Bleach
------------------------------------------
Test Results 04-28-2021 @ 08:47 PM
------------------------------------------
Free Chlorine: 17.5
CSI: -0.03
------------------------------------------
Maintenance 04-28-2021 @ 01:01 PM
------------------------------------------
Brushed
Pressure: 17
------------------------------------------
Chemical Addition 04-28-2021 @ 01:01 PM
------------------------------------------
+ 107 FluidOunces of Bleach
------------------------------------------
Test Results 04-28-2021 @ 01:01 PM
------------------------------------------
Free Chlorine: 17.0
Temperature: 75°F
CSI: -0.03
------------------------------------------
Chemical Addition 04-28-2021 @ 07:26 AM
------------------------------------------
+ 96 FluidOunces of Bleach
------------------------------------------
Test Results 04-28-2021 @ 07:24 AM
------------------------------------------
Free Chlorine: 17.5
pH: 7.8
CSI: -0.03
------------------------------------------
Maintenance 04-27-2021 @ 03:58 PM
------------------------------------------
Brushed
Pressure: 17.5
------------------------------------------
Test Results 04-27-2021 @ 03:57 PM
------------------------------------------
Free Chlorine: 21.0
CSI: 0.16
------------------------------------------
Notes 04-27-2021 @ 01:23 PM
------------------------------------------
Started SLAM with CYA 55. added 308 oz bleach to hopefully bring FC from 7.5 to 22.
Need to maintain FC 22 over next several days.
------------------------------------------
Chemical Addition 04-27-2021 @ 01:21 PM
------------------------------------------
+ 308 FluidOunces of Bleach
------------------------------------------
Chemical Addition 04-27-2021 @ 01:11 PM
------------------------------------------
+ 23 FluidOunces of Baume31
------------------------------------------
Test Results 04-27-2021 @ 01:06 PM
------------------------------------------
Free Chlorine: 7.5
Combined Chlorine: 0.0
pH: 8.0
CYA: 55
CSI: 0.16
------------------------------------------
Maintenance 04-27-2021 @ 01:06 PM
------------------------------------------
Pressure: 17.5
------------------------------------------
Notes 04-27-2021 @ 11:57 AM
------------------------------------------
Noticed yellow algae bloom near steps. Poured 64 oz bleach near steps with pump off. May need to SLAM.
