First SLAM, Need Advice

dclynds

Well-known member
Apr 29, 2016
84
Houston, TX
Pool Size
17500
Surface
Plaster
Chlorine
Liquid Chlorine
Hi All,

I stupidly let my FC drop to 0 last week and am paying for it now due to the appearance of yellow algae on the walls. :oops: On Saturday morning, I started the SLAM process for CYA 30 targeting 18.5 PPM FC (mustard algae level) at least twice a day. The OCLT from Sunday night into Monday morning was only 1 PPM, but I wanted to keep the SLAM going figuring that only 2 days of SLAM seemed insufficient. I redid the OCLT this morning (Monday night into Tuesday morning) and it was a 3.5 PPM FC loss. I did backwash and recharge the filter yesterday, but would doing so account for an OCLT increase day over day? I would still expect to see the OCLT value decrease every day, not increase. Also, should I keep my main drain and waterfall open to circulation during this process? I had the waterfall valve open for the first 24 hrs of the SLAM and the main drain open for the first 48 hrs, but have since closed them both off (I don't want my pH to increase too much due to the waterfall, and the main drain I shut off when I vacuumed my pool using that skimmer yesterday). Any advice would be appreciated. My pump has been running non-stop since Saturday morning except when I switched it off and on yesterday to backwash the filter. I am using bleach 8.25%. Thanks! Oh, and I know I made a bonehead move neglecting my FC. I will never let it drop below the recommended level for my CYA ever again.

Recent Logs
6/23 12:22 - FC 6.5, pH 7.2, TA 85, CH 325, CYA 30 - START SLAM to 18.5 PPM - added 317 floz bleach
6/23 19:27 - FC 14.0 - added 119 floz bleach
6/24 07:58 - FC 16.5 - added 53 floz bleach
6/24 19:12 - FC 11.5 - added 185 floz bleach
6/24 20:56 - FC 16.5 - no bleach added, start OCLT
6/25 06:38 - FC 15.5 - OCLT result 1 ppm loss - added 80 floz bleach
6/25 15:45 - FC 11.0 - backwashed filter - added 198 floz bleach
6/25 20:45 - FC 18.0 - no bleach added, start OCLT
6/26 06:58 - FC 14.5 - OCLT result 3.5 ppm loss - added 106 floz bleach
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
44,923
Laughlin, NV
Pool Size
6000
Surface
Fiberglass
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-40
FYI - you are to run a regular SLAM Process to completion and then, if necessary due to mustard algae, raise the FC to that level for 24 hours only.

You are just wasting chlorine by running your FC above SLAM level.

Take care.
 

dclynds

Well-known member
Apr 29, 2016
84
Houston, TX
Pool Size
17500
Surface
Plaster
Chlorine
Liquid Chlorine
I haven't had an issue with cloudiness. The water has been very clear the whole time. I just tested again for the OCLT and have a 12.5 ppm. Will see what it shows come morning.
 

dclynds

Well-known member
Apr 29, 2016
84
Houston, TX
Pool Size
17500
Surface
Plaster
Chlorine
Liquid Chlorine
I had an OCLT result of 1.0 ppm. Should I continue the SLAM? Also, the pump has been running nonstop since Saturday during this SLAM. Is that correct that I am to leave it running 24 hrs a day through the SLAM process?
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thecoolpool

In The Industry
Jun 18, 2018
12
Milford
Per the SLAM requirements under Pool School, you are done with SLAM when:


  • CC is 0.5 or lower;
  • You pass an OCLT (ie overnight FC loss test shows a loss of 1.0 ppm or less);
  • And the water is clear.

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels and you no longer need to run your pump 24/7 :kim:


 

tstex

Silver Supporter
Aug 28, 2012
1,946
Houston, TX
dc,

Just finished a mustard algae SLAM.

First, you bring your pH to 7.2, then initial FC to your FC/CYA chart level and keep at first SLAM level for 24 hrs...mine was 20
while doing this, keep your pump running 7x24, circulate the SLAM level FC in all pipes and water features..and brush entire pool real well. Hit skimmers inside all places and clean out all organic materials too.

Next day, you raise your FC for mustard algae, mine was FC = 29. This is the needed 1-2 punch. make sure you again circulate to all areas:spa and all water features...once you get to your elevated level, brush the pool again...recirculate again.

Finally, you can start your OCLT testing and other guidelines to determine any FC losses and CC levels...follow TFP guidelines...Also, I brushed real well around all my lights, returns and odd angles of the pool - I was told the biofilms of the m-algae needs to be broken for the CL to kill it. I bought a very good wide and stiff bristled brush..about 20-22" wide and I did 4-6 inch movements so each area was hit vigorously 3-4 times.

good luck, tstex
 
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