not generating Chlorine?

[TomHunt]

Using the TF100, we have been trying to get our SWG to generate the correct amount of FC. Once we rec'd the TF100, we found that FC had hit 14ppm (Pinch and Leslie had us at 4 and 6). We shut down the SWG for 3 days, got it down to 4 all the while SW FL rec'd a ton of rain and restarted at 40% (was at 70%). Our test numbers have all been good.
6/13/2017
FC 4
TC 4
CC 0
CYA 60
pH 7.8
TA 100
CH 375
salt 3200


The FC varied from 1 to 5 as we kept adjusting the SWG to different percentages.
Water has and continues to be crystal clear. But now we can't get the SWG to generate enough chlorine. The last two days the FC has dropped to <2. The SWG is at 100% and been there for three days. We added a gallon of bleach to the pool through the day yesterday getting the FC back up to >2 briefly, but this AM it is down to <1ppm.

Yesterdays tests;
FC pre-bleach <1 to 2
after bleach FC 2-3

CC 0
CYA 70
pH 7.5
salt 3200
TA 90
CH 375

Our variable pump is running at 1600 rpm 24/7. The filter is clean. We had been adding granular CYA this past week to get the CYA up. The pool is and remains very clear. The attached picture is of the 6-1/2' deep end. The black pebbles are black pebbles. The larger black thing on the bottom is one of a series of small rocks marking the swim lane.

How do I test my Jandy SWG? I don't see any sign of algae and the pool is only used by my wife and I for laps.

 

[mknauss]

There is a good chance with your periods of FC well below the minimum for a CYA of 70 (see FC/CYA chart - Pool School - Chlorine / CYA Chart) you have the start of an algae bloom. I would suggest doing an OCLT Pool School - Perform the Overnight FC Loss Test (OCLT) tonight. There is a good chance you need to SLAM - Pool School - SLAM - Shock Level And Maintain

Take care.

 

[TomHunt]

Thanks for the reply. I bleached up after dark last night and did the OCLT and in fact did end up losing almost all my chlorine over night. Heading off to Wal-Mart for bleach now.

Thank you.
Tom

 

[TomHunt]

For giggles, I took a tape measure to my pool today to verify the gallons that the pool installer said it would be. I get 1900 gallons less, 17,300 instead of 19,200. They must calculate to the top of the pavers? Outside dimensions are all right, but actual water depth comes in less than the pool construction contract. In fact, we end up with 6' deep at the deep end instead of 6-1/2' etc.

 

[TomHunt]

An update; Added Muriatic Acid Sunday AM to follow the SLAM rules on pH after my OCLT overnight FC drop Saturday PM; Then shut off the SWG and started adding bleach to my what I think is a crystal clear pool to hit the high side of target SLAM Chlorine levels for my CYA level. She gets a scrubbing every day (3 so far), but there is nothing visible coming off.

Sunday PM at 8:30 37 ppm
Monday AM at 5:30 28.5 ppm <8.5

Monday PM at 8:30, 41.0
Tuesday AM at 5:30 35.5 <5.5

Nicely cloudy sky and rain showers the past few days to help me keep chlorine in the pool with the occasional gallon of bleach added. The pool is still crystal clear. From my numbers, I am making progress??? Any guess on how much longer I should expect to SLAM? CYA is still 55 to 70 depending on if it is me looking or the wife.

Thanks,
Tom

 

[Jimrahbe]

Tom,

Time wise, each SLAM is different, but the finish is the same for everyone...

You are done 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.

Thanks,

Jim R.

 

[AftonJeeper]

Worse case your CYA is 70 and you are pushing FC up to 41? Personally I wouldn't go that far over the recommended shock level of 28.

To be clear are your 8:30pm numbers what you were shooting for or what the water tested at? I ask because variables come into play when "aiming" for a number and if you can't pass the OCLT because of these variables it would be very frustrating.

 

[TomHunt]

Thank you for thinking about my problem. The 8:30 numbers are tested numbers. I didn't want to let the chlorine drop below the SLAM recommended ppm over night. Also in the back of my mind I worry that this whole problem is mustard algae or some really nasty thing and extra chlorine is necessary.

 

[TomHunt]

Sunday PM at 8:30 37 ppm
Monday AM at 5:30 28.5 ppm <8.5

Monday PM at 8:30, 41.0
Tuesday AM at 5:30 35.5 <5.5

Tuesday PM at 9:00 43 ppm
Wednesday AM at 5:15 37.5 so <5.5 ppm

Scrubbed again this am, still nothing coming off the wall or floor with the brush. Pool water still looks very clear.

AftonJeeper, based on your comment, I will run the FC down to closer to 30 ppm today and tonight.

 

[AftonJeeper]

Hopefully that will do it. Maybe try waiting an additional 15-30 minutes between adding chlorine and testing the water. You could be getting a concentrated area of water for your PM test and a fully diluted test in the morning???

 

[TomHunt]

Thanks for the notion. I will give it some extra time.

 

[TomHunt]

SLAM took until today, so started Sunday and finished Friday AM. Now, once the chlorine gets down to 8 or so, turn on the SWG and see if it can keep up. Thanks for the help!