2+ Weeks into SLAM and .... now what?

[mfork00]

I started a SLAM on July 30th. CYA was ~70 putting my SLAM level at 28. The night of Thurs, Aug 10 to Fri, Aug 11, I thought I was going to be done in a day - only had 1.5PPM of chlorine loss (it had steadily been decreasing every night). That day, for the first time in a week or more, I threw my vacuum in to clear up some debris and got a few pool floats out. The next night, I lost 4.5 PPM, definitely a step back. Saturday and Sunday had a heavy bathing load - lots of kids, lots of floats. I added chlorine regularly and definitely saw a big uptick in chlorine usage - where as I had been using 4 gallons of 10% a day, Sunday I used 6 gallons and Monday (yesterday) 7 gallons. Overnight last night I still lost about 4PPM.

This morning, I decided to re-test my CYA to see where it was at and it came out < 20 (I could clearly see the dot even with the container full). I ran the test twice to confirm. Same result both times. I am using the same TFTestKit.net test today as I was a week ago.

In the middle of my SLAM, I had a SWG installed. My salt level was ~2800 when first tested, I added a single 40lb bag of salt on Saturday, pushing me between 3000 and 3200. I turned on the SWG only on Sunday during the day when I was burning through Chlorine, it has been off otherwise.

My question - where do I go from here?

Do I add CYA to get back to 30-40, let me chlorine levels drift down below 10 to get accurate readings on PH / TA / etc. and get in line, then finish my SLAM and push CYA to 70-80 for SWG when done?

Also - what could have been the source of the new algae? In hindsight, should probably have left the sweeper in the pool throughout the SLAM to make sure it was cleaned, but I wiped it down good when my FC dropped after adding it and saw no visible signs of algae. The likely source seems like our pool floats - do I toss them and start over?

As always, thank you all for your advice! This is an invaluable community.

 

[HermanTX]

If you tested your CYA twice and it is 20 then that is a cause for using so much chlorine. With a CYA under 25, you are losing all your FC in about 3-4 hrs. Thus you need to keep adding to supplement it. Could your original test of 70ppm for CYA been inaccurate?

Is your pool water clear?
Suggest you post a full list of all the test values - FC, CC, pH, CH, TA, CYA and Salt

Your pool toys surely could have introduced algae but you can clean them. Best to do so with air in them so you expose all the crevices. Use a mild laundry bleach with water to scrub them.
Same with your pool vac.

Do you have any ladders or other items in the pool? Have you checked behind the light fixtures?

If you test again and your CYA is still below 20, then bring it up to 30-40 to complete the SLAM. There is no harm in turning on your SWCG other than you are consuming some of its life (total hours).

 

[mfork00]

If you tested your CYA twice and it is 20 then that is a cause for using so much chlorine. With a CYA under 25, you are losing all your FC in about 3-4 hrs. Thus you need to keep adding to supplement it. Could your original test of 70ppm for CYA been inaccurate?

I don't believe my original CYA test was inaccurate. I had been tracking it over the summer using the TFTestKit.net tests and had periodically checked my values against pool store readings.

Is your pool water clear?

Yes, it has been clear since about Day 3 of the SLAM. I was on vacation, Chlorine was missed one day, came back to a green-tinted pool.

Suggest you post a full list of all the test values - FC, CC, pH, CH, TA, CYA and Salt

Just re-tested: FC 19.5, CC 0.0, TA 120, CH 300, CYA 10, Salt 3400, Temp: 88.
Did not test PH as forums said unreliable with FC over 10

Your pool toys surely could have introduced algae but you can clean them. Best to do so with air in them so you expose all the crevices. Use a mild laundry bleach with water to scrub them.
Same with your pool vac.

How about the foam filled floats that we have - at least one has a small rip in the side that exposed the foam - I put duct tape over it and it has held up ... but could that be a source?

Do you have any ladders or other items in the pool? Have you checked behind the light fixtures?

Cleaned the baskets and weirs. No ladders or others items. Lights are nichless, nothing to come out, I did scrub the lights and the returns good with a brush.

If you test again and your CYA is still below 20, then bring it up to 30-40 to complete the SLAM. There is no harm in turning on your SWCG other than you are consuming some of its life (total hours).

 

[HermanTX]

I don't believe my original CYA test was inaccurate. I had been tracking it over the summer using the TFTestKit.net tests and had periodically checked my values against pool store readings.

CYA does not evaporate out and while CYA can dissipate 5-10ppm over time, it is a slow process. So based on the current test is 20, add stabilizer to get to 30-40.

 

[mfork00]

Thanks for the help @HermanTX. Just re-checked my FC now and it was 6.5. Since FC was < 10, I used the opportunity to check the PH (~7.9). Added 1/2 gallon of bleach, enough muraitc acid to drop the PH to 7.2 to work on the TA levels, and then put 2 pounds of CYA in socks to dissolve over the evening. Will manage FC against SLAM levels for 20 CYA overnight and retest CYA in the AM.

 

[HermanTX]

Thanks for the help @HermanTX. Just re-checked my FC now and it was 6.5. Since FC was < 10, I used the opportunity to check the PH (~7.9). Added 1/2 gallon of bleach, enough muraitc acid to drop the PH to 7.2 to work on the TA levels, and then put 2 pounds of CYA in socks to dissolve over the evening. Will manage FC against SLAM levels for 20 CYA overnight and retest CYA in the AM.

It may take 24-36 hrs for CYA to fully mix and register on your test so if your initial CYA test does not meet your desired level, wait 12 hrs and test again before adding more stabilizer.

 

[JupiterFL]

When you add cya, you assume it’s there, and does your chlorine accordingly.