2nd SLAM

[CFH]

So I've lurked here for awhile and learned a lot since my new pool was completed last October. What an excellent resource this forum has been for me!

In early February, I let the pool go about three days without testing. when I pulled the cover off the next day, the pool was grayish and a little murky. (my plaster is gray) I immediately tested a sample and found FC at zero.

So, having already read all about algae and the SLAM, I knew what I had to do, and I went ahead and completed my first SLAM, which took about 1 week. After a week and a half, FC got back down to 7 with the SWG off. I was back to my regular routine of checking the water balance every other day and doing a full range of tests on the weekend.

Things were normal for about 1 week. Then, last Sunday AM FC was at 3.5 after having the SWG on at 20% and FC 5 on Friday. So I bumped the SWG to 60% output. CYA was 55 and so I also put about 1-1/2 lbs in a sock in the skimmer to try to approach a target of 75. By Sunday PM FC was 4.5. The pool looked clear and we swam that day. I left the SWG at 60%.

Monday afternoon, I uncovered the pool and found a dead Armadillo in the bottom of my pool. Yuck!

After removing the intruder, I tested FC and found it at 5.5, and left the SWG at 60%.

By Tuesday AM, the FC was down to 3 and the water was cloudy. So I began another SLAM by adding chlorine, brushing, vacuuming, and then cleaning the cart.

Yesterday morning FC was 19. I added 3/4 gallon of chlorine. 3:45 PM FC was 26. 8:30 PM FC was 20.5 Last night I added 1 gallon at 9:30 PM. I tested at 11:15 PM and got FC 34 CC .5. This morning at 7 AM I got 28.5 and ran out of reagent so I couldn't test CC.

My pool looks great, and the filter was pretty clean Sunday after a two day run. I am still consuming lots of chlorine, in fact it doesn't seem to be getting better. I added 1-3/4 gallons of 10% bleach total yesterday. We also swam and had the cover off all day and all last night. I'm estimating my CYA couldn't be above 65, and therefore I am targeting FC 26 as shock level according to pool math. During this SLAM, I have tested at least twice per day, and FC has not gone below 19.

Any advice? Do I just need to stick it out a few more days? How much impact does swimming for a couple of hours have on FC? We are a family of four.

 

[kris77]

My guess is the first SLAM wasnt 100% complete when you stopped and it took a week or so for the pool to turn again.

Be sure to follow the SLAM process exactly.

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.

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels.

 

[tim5055]

What is your CYA and what are you testing with?

Better yet, a full set of test results please.

 

[CFH]

My guess is the first SLAM wasnt 100% complete when you stopped and it took a week or so for the pool to turn again.

Be sure to follow the SLAM process exactly.

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.

When all three are true, you are done SLAMing and can allow the FC to drift down to normal levels.

Maybe, but I thought all three were satisfied, the one that took longest was the OCLT.

Could be I rushed it.

 

[CFH]

What is your CYA and what are you testing with?

Better yet, a full set of test results please.

Last full results before 2nd SLAM on Sunday 2/29/2015 9:20 AM:

FC 3.5
CC 0
TAC 3.5
pH 7.6
TA 90
CH 225
CYA 55
Salt 3100

I added 8 oz of acid that day.

Partial results Monday 3/2/2015:

FC 5.5
CC 0
TAC 5.5
pH 7.4

Partial Results Tuesday 3/3/2015:

FC 3
CC 0
TAC 3
pH 7.4

That's the day I started the 2nd SLAM.

As stated previously the CYA Friday before the 2nd SLAM was 55. That day I added about 1-1/2" lbs of dry CYA in the skimmer to attempt to approach the recommended level of 75 for SWG pools.

I'm using the TF-100 with the speedstir and the Taylor K-1766S Salt Test Kit

I also keep a log of all test results.

- - - Updated - - -

Thanks for the replies, I'm grateful for the help. It's good to know I'm not in this alone.

- - - Updated - - -

I think I meant to say "Sunday 3/1/2015" and not "Sunday 2/29/2015". Duh.

 

[tim5055]

Well, Tuesday your FC was at the very bottom of your "safe" range for a SWG pool.

Now that you have added more CYA (never add it to the skimmer by the way) your absolute minimum is now 4 with a target of 6. The bad thing is that now that you added CYA your shock level is now 31.

SLAM again and don't stop until:

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.

The more often you test and adjust your FC back up to 31 the quicker it will go.

This is what your day should look like---

Test FC
Adjust FC to 31
Wait an hour or more
Test FC
Adjust FC to 31
Wait an hour or more
Test FC
Adjust FC to 31
Brush
Wait an hour or more
Test FC
Adjust FC to 31
Wait an hour or more
Test FC
Adjust FC to 31

 

[CFH]

Yes Tuesday FC was at 3. That was the day it went south. Maybe I need to run my pump later into the day to keep up with the sunlight destruction of chlorine, because the previous day it was 5.5 at 3:30 PM. It currently shuts off at 4PM (when not SLAMming).

Here is some data regarding the current SLAM:

Tuesday:
9 AM FC 3 Added 2 1/2 Gallons
12 PM FC 24
4:45 PM FC 19.5 Added 1/2 Gal
7 PM FC 25

Wednesday:
7:45 AM FC 20 Added 1-1/4 Gal
7:15 PM FC 29.5

Thursday:
7:15 AM FC 24 Added 1/2 Gal
1 PM FC 26 Added 1/4 Gal
4:30 PM FC 28.5
7 PM FC 24 Added 1/2 Gal
9:45 PM FC 32.5

Friday:
7:35 AM FC 30
12:45 PM FC 26.5 Added 1/4 Gal
8:30 PM FC 30.5

Saturday:
7:30 AM FC 24 Added 1/4 Gal
4 PM FC 27
9: PM FC 26

Sunday:
7 AM FC 24 Added 1/4 Gal
1:41 PM FC 22 Added 1/4 Gal
10 PM FC 22.5

Monday:
7:30 AM FC 19 Added 3/4 Gal
3:45 PM FC 26
8:30 PM FC 20.5
9:30 PM Added 1 Gal
11:15 PM FC 34

Tuesday:
7 AM FC 28.5

Out of reagent. Its 4:30 PM I haven't added any chlorine today, can't test. So I guess I'll guess and add 1/2 gal now and maybe another 1/4 after dusk?

 

[CFH]

Well, Tuesday your FC was at the very bottom of your "safe" range for a SWG pool.

Now that you have added more CYA (never add it to the skimmer by the way) your absolute minimum is now 4 with a target of 6. The bad thing is that now that you added CYA your shock level is now 31

Ok I can target 31, although I think I have probably been there a lot of the time anyway because I overshoot the chlorine to compensate for when I cant babysit the pool every hour. Maybe this is why I seem to be going backwards.

According to Pool Math, adding 1-1/2 lbs (24oz) of CYA to my pool at 55 would bring it to 72. I was targeting 26 assuming CYA would have reached 65. Remember I cleaned the filter cart right after adding the CYA. And 24 oz is just a conservative guess on what I added anyway. I had what I think was 1/2 of a 4 lb bag and added a little over a half of that but didn't weigh it. I could weigh what's left but it will still be a guess because I never weighed out the first part of that bag either.

Unfortunately there is no way to test CYA accurately right now, is there?

 

[tim5055]

I'm confused---

You show testing up to five times a day, but only adding chlorine once or twice. Every time you test you should be adding chlorine to bring the FC up to shock level. If you don't plan on adding chlorine, don't waste the reagents to test.

You want to try to keep the FC at shock level, not just get there once a day.

 

[CFH]

Yeah, I was targeting 26 and kept it above that until Sunday night. I thought based on the previous night I might be done.

Monday I ran out of Chlorine and had to go get some. Now I'm out of reagent.

So for those of you reading this and learning like I am, I cant stress enough that you need to prepare properly!

So I guess I'll regroup with 31 as a target and figure out some way to get some reagent, I checked the two pool stores here today and nobody has even heard of FAS-DPD Haha!

 

[tim5055]

So I guess I'll regroup with 31 as a target and figure out some way to get some reagent, I checked the two pool stores here today and nobody has even heard of FAS-DPD Haha!

The only place I've heard of that sometimes keeps it in stock is Leslie's locations. But, even many of them are confused and just say bring them the water to test.

Is it the DPD powder or Reagent you are out of?

Leslie's has a store in town and here are their SKU #s, but their prices are obscene.

Taylor Technologies R-0870-I - DPD Powder Sku: R-0870-I
Taylor Technologies R-0871-C-12 - FAS-DPD Titrating Reagent, 2.0 oz. Sku: R-0871-C

 

[jblizzle]

Check if there is a commercial pool supply store near you, not a small retail store. They might have the FAS-DPD reagents.

 

[CFH]

Tim5055, It's the reagent. Plenty of DPD powder, but I need a barrel and tap for the 0871.

jblizzle, Good idea, there is a Gorman and other wholesalers near here. I tried Leslies today and they didn't have it stock.

I just threw in a gallon of 10% that should keep it till morning.

At least the pool looks great.

 

[CFH]

I got more 0871 reagent and let the FC come down to get an accurate CYA test and adjust pH.

Here are Sunday evening's test results:

FC 7
CC forgot to test
pH 7.4
TA 100
CH 225
CYA 30
Salt 2800

I added about 2 cups of 10% bleach Sunday evening, nervous the FC wouldn't hold overnight.

Here are today's test results:

FC 7
CC .5 or less
pH 7.6

SWG has been at 60% since Sunday evening.

Should I do an OCLT?

Why is my CYA at 30? I tested it twice. I was surprised it was so low.

 

[jblizzle]

Did you do the CYA test in the same lighting as before?

How does the water look?
I was bump the FC back up, turn the SWG off, and do an OCLT to see where you stand.

 

[tim5055]

Should I do an OCLT?

Why is my CYA at 30? I tested it twice. I was surprised it was so low.

Have you ever fully completed the SLAM by attaining all 3:


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

As to the CYA, it really can only be one of several things:

Substantial water exchange
Testing error when you got the 55 result
Testing error when you got the 30 result
Testing error both times and the true result is somewhere in the middle

By far the CYA is the hardest test. I see a 10 swing between testing on a bright sunny day and an overcast day.

 

[CFH]

I completed the 1st SLAM in February, but I could not definitively complete the 2nd SLAM because I ran out of reagent.

The pool looks great, like crystal clear. I can see the individual pebbles in the finish at the deep end.

I looked at my logs and found I have performed the CYA test at least 20 times. I have read and followed both the TF-100 instructions and the more in depth instructions posted here on the forum. I think I have it right. I had my pool service owner friend take an independent read of the same sample one day and we both got 55-ish, whatever that is worth.

My pool area is surrounded by white vinyl fencing. Typically testing is done on a sunny day with back to sun, viewing tube at waist level.

I realize the test is ballpark-ish and subjective. I consider that when testing, however, and have had fairly consistent test results that I have confidence in.

That said, I have noticed a trend of gradually falling CYA (and salt) and have considered I might have a leak.

This is a relatively new pool, any chance that figures in this?

 

[tim5055]

That said, I have noticed a trend of gradually falling CYA (and salt) and have considered I might have a leak.

This is a relatively new pool, any chance that figures in this?

Not sure the new pool would figure in, but if you had a leak and were filling with tap water that would explain falling CYA & salt. Do you have an auto-fill?