Starting a Slam and Wondering What Happened

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treyrich

treyrich

Gold Supporter
Aug 23, 2022
141
Orange County, CA
Pool Size
22000
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Ok, so I have been as diligent as possible in testing and balancing my water since my pool was finished a couple of months ago. I test every morning and have kept everything in line as much as possible. In mid-june I did a very small slam due to not passing an OCLT, once I was passing though I let things settle down and attempted to maintain the FC at the highest level of the recommended range for the CYA.

Fast forward and we did a lot of traveling in the last 2 weeks, during which time our auto-cover was on nearly 100% of the time. Everything seemed more or less in line, except for the last 6 days the cover was on 100% of the time (except when the PB came by to add the mastic to the pool finally, which resulted in a decent amount of sand making it into the pool/spa). Before leaving I spiked my SWG up to a higher level than normal thinking it would be a little extra insurance. When I returned home yesterday the first thing I did was tested the water and found that we had 0 FC! I quickly ran down to Walmart last night at 10PM and bought 10 gallons of liquid chlorine and spiked the FC up to SLAM level and have been brushing and testing and adding more chlorine this morning.

So, my questions are these:
  1. How did this happen, and how could I have avoided this situation? I'm confused by the fact that chorine wasn't being eaten before I left at a very fast rate, then the pool was covered allowing little-to-no UV/light into the pool to burn off FC or to promote algae growth. I'd love to better understand what may have gone wrong here and how I could have planned better for this trip.
  2. I've had a really tough time determining my CYA, I'm wondering if it's possible that by misreading the CYA test that I possibly wasn't running my FC as hot as I thought I was?

Anyhow, it seems I'm in for a SLAM so I'll update this thread as I go along so that those wiser than myself can help steer me right. Here's the Pool Math overview from this morning for those that don't want to dig through my logs.

==========================================
El Berro
------------------------------------------
Build Type: Plaster
Volume: 22000 gallons
------------------------------------------
Latest Test Result Summary:
FC: 18.0 (3 hours ago)
CC: 0.0 (3 hours ago)
pH: 7.8 (13 hours ago)
TA: 90 (16 days ago)
CH: 275 (16 days ago)
CYA: 60 (7 days ago)
SALT: 3200 (16 days ago)
TEMPERATURE: 85° (3 hours ago)
CSI: 0.02 (3 hours ago)
==========================================
 
Seems like everything was fine until the pool tech did their work. I would be suspicious of their activity and any product(s) they may have allowed into the pool. Regardless, at this point all you can do is try to bounce back via the SLAM Process to get your levels back to where they used to be. Being vigilant with your testing may have saved you a much longer SLAM process.
 
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That would be reassuring if it was when they did their thing, because at least then it would have only been sitting for 1-2 days with low-zero FC. Luckily them doing the mastic was the last thing that they have to do, so at this point the construction is completely done. I wish I knew exactly what happened to store away in my memory bank for the future, but I guess any number of things could have happened and the only thing that I know for sure is that a good deal of the sand that they used on the mastic made its way into the pool, so maybe there was something nasty living in that sand...
 
Ok. So I've been going on this slam since last Wednesday night ~4.5 days. After day 1 the water was crystal clear again, and the CC has never been higher than 0.5, however I just can't seem to pass the OCLT so I'm continuing on. On Saturday I cleaned the cartridge filter out (was not very dirty at all, but I figured every little bit helps). I figure I've got to be close to finished here?

Here's my ultimate question. Since starting this SLAM I've been running my pump at a high speed ~2700 RPM 24/7. Does SLAM protocol call for running at a high speed? Or just running? I'm wondering if I can now back down to my regular schedule where it only ramps up to high speed when skimming/suction side cleaner and the rest of the time we're running at low speed?
 
Ok, I finished my slam, but now I’ve got something else going on. My CYA seems to have dropped off completely during the slam.

Before the slam I tested somewhere between 50-60 (I thought 60 my wife thought 50) so I called it 60. Then during the slam I retested and it was clearly 50 so I stuck to 50 for the remainder of the slam. Now that I finished I wanted to get CYA back up to 60 so I started adding small amounts of dry stabilizer trying to inch my way there. However after the first 19oz of stabilizer CYA was completely off the charts low (could see the dot the whole time), so I ran the test again and again it was super low, so I added another 13 oz of stabilizer and now it seems like it’s around 40.

I’m worried about adding more stabilizer for fear that I may actually be higher than I think. The only difference between tests is that I had to open a new bottle of reagent because my previous one ran out. Is it possible that the reagent is somehow less potent? I ordered more thinking that in a few days I can test that theory.

What should I do? Keep adding stabilizer? Wait for the new reagent? Something else?
 
Ok. I checked a couple of times yesterday and again today and my tests all are the same. I'm still testing ~40. I guess at this point it doesn't hurt to wait for the new reagent to arrive before adding more stabilizer, might be another day or two.

If this number is right I'm extremely confused about where the CYA could have gone. I had my autofill off for most of the SLAM to ensure that new water wasn't being added throwing my chlorine usage off, and it hasn't rained at all, so there's no way that I could have had any amount of significant water replacement. And the pool is only a few months old, so I doubt that the CYA has degraded? All signs are still pointing towards some disparity between the reagent bottles in my test kit in my mind...but if that's not the case I'm not really sure what to think?
 

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Interesting...So maybe some of that bacteria was on the sand used for the mastic, and that's why there was such a huge drop in FC so quickly. I think that could explain everything.

So then (working under the assumption that this was the problem) the question becomes whether I should be trying to get more CYA into the pool ASAP, or if it's still best to wait for the new reagent to definitively rule that out?
 
Tough question. One you put it in, you can only replace water to get it out.

How old are your cya reagents? I had some left over from last season, so I have been alternating tests with my fresh reagents. I didn't have a different result between old and new.

Are you able to maintain a FC between 5 and 9 with your swcg? Do you have any historical knowledge of how much FC you lose on a hot sunny day?

I would test a few times to see if you can maintain FC. If not, your cya is probably low. you could boost with liquid chlorine, untill the reagents come in. If you can maintain, you probably have adequate cya buffering the chlorine.
 
I bought the test kit 01/10/2023, can't remember when it arrived, but sometime this year.

I really don't have great historic knowledge as the pool was only finished at the end of May and it's basically been cloudy all of May and June. However I have had my SWG off for the last week dealing with the SLAM and letting things drift down. It seems like with our level of use I've been losing about 2-3 FC per day for the last few days as we've been letting things drift down from SLAM. We have an autocover which blocks most UV, but the pool has been used 1-2 times per day on average so it's primarily during those times of use that we're seeing much loss. The autocover is another question as I'm not sure whether I should even be following the guidance for CYA levels with the SWG given the cover being in the equation?

Sounds like the best bet is to wait for the new reagents, especially since as of right now I don't have any problem keeping FC in the pool. Once the reagents do come though and I'm reasonably confident in my levels, is there a different recommendation for CYA level with SWG and auto cover?
 
Your reagents should be fine. What is the expiration date on the bottle?

I have an auto cover as well, I have been dialing in my swcg For the last few weeks and have it set pretty good.

I run cya at 60. I maintain my FC around 8.

with my cover closed, I set my swcg at 6%. With it open, it set it at 80%.

If we forget to ramp it up, I'll dose with liquid chlorine to get it back to 8 quickly.
 
There doesn't appear to be any expiration date on the bottle...It's one of the small 2oz bottles that come with the TF-Pro

RLP said:
If we forget to ramp it up, I'll dose with liquid chlorine to get it back to 8 quickly.
Click to expand...
I had our builder add the cover card to our intellicenter which lets me just set the output for cover on and cover off within intellicenter, it's really awesome, never possible to forget to ramp it up. That said, I'm definitely nowhere close to having my numbers dialed in for closed or open and this SLAM has thrown me off even more. I turned it back on today and have it set at 25% closed, 40% open, 15% spa. I run my pump 24/7 for context. I suspect that my closed output is too high, but I wanted to err on the high side than on the low and pool math told me that 25% would raise FC 2.7 and I figured that I'm losing around 2-3 a day so 2.7 made logical sense as a starting place.
 
Interesting that I personally just ran into the same thing. Everything was going swimmingly until about 2 days ago my wife said that the pool looked a little 'hazy'.

Anyways, gave it a mega cleaning, always double checked my cya/fc and it was always on mark. Today my pool is getting slammed because it's turning green. I checked and my cya is now 40, which doesn't make sense to me. My reagent is 12/24. Regardless, even if it was expired/bad, and I was measured at 40 instead of 60, my fc was still higher and this shouldn't have happened. I have no idea what caused this but it is what it is. There was a large about of debris on the bottom after a lot of raining overnight and I haven't had my filter running the past few days...
 
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So, I think that my reagents are bad, must be, the only logical conclusion. The amount of debris I just vacuumed out, the fact my FC hasn't changed since starting slam, it's the only option.
 
As soon as my new reagents arrive I'll update here. I have a hard time believing that they're bad, but it also seems like the simplest explanation (which is obviously normally the correct explanation). In the mean time I'm just going to keep my FC really high to avoid any issues.
 
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I totally agree with you, my don't expire for a while yet, if you check my logs you'll see that my fc was always in high end of target and what I just cleaned out manually was not normal. Going to dump another 52oz of LC until my new reagents arrive. Really don't have a choice at this point, lol..... lol
 
Ok. So my new reagents showed up and it appears that my previous ones were just fine and my readings were correct. I still feel like there's some kind of issue though. Yesterday I added 29oz of dry stabilizer and this morning when I tested my water didn't look quite as clear as it regularly does and my FC had dropped more than I expected. Luckily I was running my FC super hot, so I never went even close to minimum levels, but the slight lack of clarity is concerning to me.

So here's my question, based on the fact that my reagents weren't bad that means something was indeed consuming my CYA at an alarming clip, but I completed a slam which should have removed any nasties from the pool right? So is it random that the pool had a higher chlorine consumption yesterday after I added the CYA? Or is it possible that my pool is rejecting the CYA in some way?

Also, bonus question, (I'm guessing the answer is do an OCLT) since I did have a higher consumption yesterday, do I have to slam again even if I didn't drop close to minimum?
 

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