First time SLAM - 1 Week In

jamjam

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Jun 25, 2020
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While your light is out you can take the opportunity to check the ground wire. It should be encased in black potting compound. Basically a black plastic blob on the top inside of the niche. Check to make sure it is still encapsulated and the potting compound is not degraded.
 

PoolInTheRain

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May 5, 2021
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North Haven, CT
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While your light is out you can take the opportunity to check the ground wire. It should be encased in black potting compound. Basically a black plastic blob on the top inside of the niche. Check to make sure it is still encapsulated and the potting compound is not degraded.
Thanks, I will give it a look. I haven't been in the water yet as it has been too cold, but I'll see if I can spy it from another angle.

I know I've brought a number of topics in this thread, but to the original question, right now the light niche has been scrubbed as much as reasonably possible with a brush, and the deep end steps are out of the pool. I'm still curious about where we could be losing FC.

Is it possible to lose FC through the filter? Like as the water passes through? Wondering if I should backwash. I did one backwash after the opening, but since then, the pressure has not increased at all since the SLAM began.
 

Texas Splash

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Is it possible to lose FC through the filter?
Generally speaking I'd say no. Not in a serviceable filter. I say that because while water is moving, any algae trapped in the filter is exposed to a high level of chlorine and should be dead. We don't expect algae to grow in a filter with no light, but the dead material will get trapped in there which is why it's good to clean as required during a SLAM (25% pressure increase). Now if your gauge isn't moving, you need to consider perhaps the gauge is bad? When system is off it should fall to zero, then you should see various increased psi readings when on a low speed or high speed.
 
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PoolInTheRain

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May 5, 2021
27
North Haven, CT
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Generally speaking I'd say no. Not in a serviceable filter. I say that because while water is moving, any algae trapped in the filter is exposed to a high level of chlorine and should be dead. We don't expect algae to grow in a filter with no light, but the dead material will get trapped in there which is why it's good to clean as required during a SLAM (25% pressure increase). Now if your gauge isn't moving, you need to consider perhaps the gauge is bad? When system is off it should fall to zero, then you should see various increased psi readings when on a low speed or high speed.
Thank you. The gauge does fall to 0 when off, I wasn't clear. I meant that I haven't had an increase in pressure. I'm generally just puzzled as to where the FC loss overnight is. The water has looked crystal clear for over a week, and we brush and vacuum, but we get the same FC loss every night.
 

Texas Splash

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I'm generally just puzzled as to where the FC loss overnight is.
With no sun on the water, it has to be organic. This is pollen season for many. Do you have pollen around the decking or on cars in the morning? I don't want to lose my place typing, did we already address all the potential hiding places of algae in this thread (lights, drain cover, hollow steps/ladders, etc)? Any concerns there?

Any chance there could be an FC testing error or inconsistency? Water samples taken form the same place? FC allowed to mix well (about 30 min) before each test if the pump was off for some reason?
 

PoolInTheRain

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May 5, 2021
27
North Haven, CT
Surface
Vinyl
With no sun on the water, it has to be organic. This is pollen season for many. Do you have pollen around the decking or on cars in the morning? I don't want to lose my place typing, did we already address all the potential hiding places of algae in this thread (lights, drain cover, hollow steps/ladders, etc)? Any concerns there?

Any chance there could be an FC testing error or inconsistency? Water samples taken form the same place? FC allowed to mix well (about 30 min) before each test if the pump was off for some reason?
Yes, pollen is one of the things I was wondering. We did go through all of the potential hiding places (removed the light and brushed inside the niche, replaced the light after 2 days of water circulating, took out the steps ). I haven't removed the drain cover but I've brushed and gotten bristles inside the top of it quite a bit.

For FC testing, I do it the same way every time. I submerge my arm up to the elbow, from the same spot in the pool. I take a reading 30 minutes after and it's always 16 ppm. Then in the am, it drops basically 3 ppm every time.

There is a ton of pollen right now, so I'd guess that is the problem. We've had the pump running 24/7 since 5/6, so almost 14 days. Do you think it's safe to let the FC drift down to normal levels and monitor?
 

Texas Splash

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Do you think it's safe to let the FC drift down to normal levels and monitor?
Tough call. On the surface it would be easy to say no and keep the SLAM going. However I'm not the one doing it. :) By stopping, you are accepting an unusual FC loss during darkness and assuming it's pollen related. Pollen may have something to do with it, but 2 ppm is a lot to place on pollen since 1 ppm is acceptable. If you let the FC drop, the water may fall under more stress and get cloudy with more FC loss.

Before letting the FC drop, I would take a deep breath and look everything over one more time. Inspect in and under everything you can check. Check the liner for creases. Your water testing isn't linked from Poolmath to your profile, so I can't see all your numbers, but be sure to compare the CYA one more time if it's been a few days to ensure the FC is at the right level. Between all of this and accurate testing, if you can't beat the OCLT, you may have to make a change.
 

PoolInTheRain

Active member
May 5, 2021
27
North Haven, CT
Surface
Vinyl
Before letting the FC drop, I would take a deep breath and look everything over one more time. Inspect in and under everything you can check. Check the liner for creases. Your water testing isn't linked from Poolmath to your profile, so I can't see all your numbers, but be sure to compare the CYA one more time if it's been a few days to ensure the FC is at the right level. Between all of this and accurate testing, if you can't beat the OCLT, you may have to make a change.

Thanks, here is the link to the testing numbers: PoolMath Logs

I will link that in my profile as well.
 

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PoolInTheRain

Active member
May 5, 2021
27
North Haven, CT
Surface
Vinyl
I am going to check the CYA again today to be sure. I definitely did another complete check of anything anywhere that could be hiding any organic matter. We lost 5 ppm overnight, which is the most. It was unusually hot here during the day (almost 90), and the pool deck was covered with but I topped off after sunset around 8:30 pm.

IF CYA is somehow higher than it previously was, that might explain the loss.

One other quick question I have is regarding the light nice. I had a pool company come out to fix a jandy valve, and the tech put a new gasket on the pool light due to the condensation and put the light back into the pool. My question is when I was brushing in the niche, what is the likelihood of having knocked the ground wire out of place? I mainly brushed around the edge because the power cord was blocking access into the deeper recess of the niche, but I was able to get about 10" of the brush into the niche. I couldn't see into the niche, and I tested the GFCI at the circuit breaker to ensure it triggered.
 

Texas Splash

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When it comes to the niche, we typically advise owners to completely remove the light and set it on the deck with the breaker OFF to the light. This gives the owner all the access they need to the niche and also allows chlorine to flow in the cavity as algae takes time to remove if we can't get each spot manually. You should also be able to inspect the ground wire clearly. If you find the CYA to be higher than you thought, it would mean you were not maintaining the proper FC level. Losing 5 ppm overnight is quite a red flag. I would say that's more than what pollen would account for. I would start at the light again just in case and leave it out for a while.
 
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