Still failing OCLT

LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
So I started to SLAM I don't know, 2.5 weeks ago I think, it feels like I've been doing this for so long now. It took longer than it should have because I had the incorrect volume for my pool, so I spent a week or so getting close to but never hitting my FC target.

So now I have had 3 days of crystal clear water, but I keep falling my OCLT by 1-2 ppm. The first time I thought it was because it had rained that night. The next time I thought it was because we had a bunch of kids in the pool all evening. But last night it did not rain and there were only 2 adults in the pool for about 20 minutes in the evening. The pool had been vacuumed by the robot and the skimmer baskets were clear. I still lost 2 ppm. I know I ned to keep the SLAM going until I finish it, but I'm getting soooo tired of it and with my work schedule I'm down to only being able to check it 4x a day (before work, after work, few hours later, and before I go to bed).

No more piles of algae along the creases in the morning. I have cleaned out the light niche. Skimmer area looks good. Am I down to doing a deep clean of the filter?? Makes me a little nervous, but I'll do it if needed. I can see a tiny bit of something in that little glass peep hole on the filter that might be algae. It's at an angle that makes it hard for me to see it well. Doesn't go away when I backwash, but I don't know how to get the thing off to clean inside of it.

Any suggestions would be appreciated!!!
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,924
San Dimas, CA (LA County)
It's not the sight glass on the filter. That's connected to the waste line, so that if you're hard plumbed to the sewer, you can still see when the backwash runs clear. When you're in filter mode, it has nothing to do with the pool.

Sounds like you've checked all the obvious spots, skimmer throat, lights, backside of weir. That pretty much leaves filter.
 

Kjp300

Gold Supporter
Jul 18, 2018
134
Canfield ohio
I think you need to make sure no one is in the pool in the evening when you do an OCLT. I am no moderator or expert so so feel free to correct if I am wrong. But I had the same issue once where I kept failing the OCLT but my water was Chrystal clear and my cc was always less than .5. My pool gets a lot if use by my grand kids and their friends and they sometimes swim into the evening. One day no one swam and I passed the test. My thought is if people swim into the evening the chlorine is working on organics that are left behind by the swimmers which may cause a fail in the 2ppm range.
 
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LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
Thanks for the input Kjp- I was really clinging onto that hope myself. Unfortunately, no one swam last night, I vacuumed the pool, cleaned out both pool skimmers and the skimmer near the filter to make sure there was *nothing* within my control that could use up the chlorine. My OLCT was 2.5. :/ I guess I'm cleaning the filter this weekend.
 

LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
OCLT for was 2 ppm this a.m. CC is 0.5. Water is crystal clear. I'm *so* close. So I mentally prepared myself for a deep clean of the sand filter and my worry that I will break something or not be able to put it together. Then I realized I couldn't get the dome off the filter. After much googling I learned that I need a special wrench to do this, which I was able to locate at a nearby pool store.

As the guy at the store was checking me out he started asking me questions about what I was doing. Long story short he told me that if I had my chlorine at shock levels for 3 weeks then any algae in my filter would be dead. He said it was probably nitrates in my pool that were using up the chlorine. He said I could do some kind of chlorine demand test through the pool store to confirm that it was nitrates, but that they couldn't give me the results until Monday. He said I could fix it without a deep clean of the sand filter (and without removing the filter dome) if I dumped a certain chemical in the skimmer basket near the filter and let it sit for 24 hours. He said the chemical cost the same amount as the wrench (and then I wouldn't need the wrench), so I don't think he was trying to sell me a bunch of stuff. I bought the wrench anyways and told him I would be back if I needed more help.

Can someone please weigh in on this and help me make sense of it? I'm so tired of this SLAM that I just want to be done with it one way or another.

Thanks!
 

LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
Update...not sure if I need to move this to a different post category...

So I used the wrench to take off the dome, but it doesn't look like what I expected in there. This thing is in the way of me seeing or getting to the sand. I pulled up on it gently to see if it I could move it, but it doesn't move easily. I'm worried that if I pull too hard I'll pull the whole lateral thing out of place and mess it up. Any help would be much appreciated.
pool 3.pngpool 2.png
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,637
Laughlin, NV
Can you add what brand and model sand filter this is to your signature?

The sand was originally poured into the filter via that dome. So you must be able to get to it from that spot.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,637
Laughlin, NV
If this is a Hayward SX style sand filter, wait for someone with experience with that filter. I think to get to the sand you have to take apart the filter another way.
 

LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
I believe it is a Hayward S200 and I've updated my signature. I'm starting to think I need to take the big part of the dome off...

I also saw that I need to make sure the filter is separated from the plumbing to prevent the crud going back into the pool. Is turning the valve to the closed position sufficient for this?
 

LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
What about the whole "nitrates using up the chlorine" theory? Is this a thing? Could I have a nitrate problem rather than an algae problem? It does seem odd to me that I could have my chlorine at this level for so long and still have algae living anywhere the water touches.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,637
Laughlin, NV
Wait on someone with experience with that filter. I do not have any.

Nitrates are not a thing. Great sales pitch though. Follow the FC/CYA Chart. Eradicate algae.

Algae can be quite sneaky. Light niches, ladders, drop in stairs, weir doors, skimmer throats, etc. It creates a resilient bio-film resistant to chlorine. So brushing, etc is needed to break it up.
 

LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
We removed the larger dome with the plan that if we messed anything up we would call the guy that opens and closes the pool to rescue us. It was a mess in there - big layer of gray gunk on the top of the sand and smaller green chunks everywhere inside. I rinsed it for an hour and a half. At one point my son and I were scooping sand into the skimmer and "panning for algae" as he called it. :) We got it all put back together, then had a huge storm that left a ton of leaves in the pool, filling up the skimmer basket and crowded around the skimmer door and the bottom filter. Ugh. So I cleaned most of it up but there's still some in there and I'm tired and I need to go to bed. I'm not sure if all the leaves will throw off my OCLT tonight, but my fingers are crossed.
 
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LHK

Silver Supporter
Jun 11, 2020
31
Cincinnati, OH
Update: my OCLT was 1 this am, despite all skimmers/floor drains being filled/covered with leaves. CC 0.5. Water is crystal clear. Big sigh of relief.

THANK YOU to everyone who responded with suggestions, input, and users manuals. It is so very appreciated and hopefully I can keep it in great shape for the rest of the season!

Laura
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
32,637
Laughlin, NV
Great Job!
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Kjp300

Gold Supporter
Jul 18, 2018
134
Canfield ohio
Thank you. Member here for two years after being “pool stored” and have not been to the pool store since. I feel completely in control of my pool. The experts and folks here behind the scenes do an outstanding job and they are all volunteers. Thanks again.