How many days of SLAM/OCLT?

[Red]

My pool water has been clear and looked fine; however, I've felt that I've been having to add a lot liquid chlorine to help my SWG. I looked at my records and saw that I've also been running my SWG slightly higher than usual. I kept things in order by adding liquid chlorine through a few parties and now we have a short lull, so I tried an Overnight Chlorine Loss Test. It failed. I started to SLAM Process. What's unusual is that now I'm on my third day of failed OCLT after staring to SLAM. For me usually 1 night has been sufficient, or maybe 2, to get everything back in order.

Here's where I'm at:

When	OCLT FC Loss
1st Night: Saturday - Sunday	3.0
2nd Night: Sunday - Monday	2.0
3rd Night: Monday - Tuesday (today)	1.5

Is it encouraging news if my OCLT FC loss continues to get less each successive night and I just need to keep at it, or is that not a useful observation? My filter pressure hasn't gone up. When I brush, I don't see anything come up. I've been raising FC to 24-25 each night. Per the FC/CYA Levels, I only need to be at 20.

For the record, here were my test results on Saturday before I started SLAMing:

Test	Result
FC	6.5
pH	7.4
TA	70
CH	425
CYA	50
Salt	3500 (as reported by cell, not drop test)
Temp	78

 

[Richard320]

You are showing progress, but obviously something is still alive in there. It is time to scrub steps and ladders and behind lights and inside skimmer throats. Somewhere the algae is still growing in a protected space and then coming out to cause problems. Looking at your signature, I'd also recommend running the slide and the spout and anything else to flush things out with heavily chlorinated water.

 

[Red]

Thanks for your thoughts. I flushed out the umbrella holder yesterday, but didn't consider some of these other things. I'm also running some water through my pool cleaner line now. I try to do that periodically (as I use a mechanical cleaner), but hadn't thought to do so at this time.

 

[Pool_Medic]

I would suggest you’ve not removed it all and your cya is low.

 

[Red]

I would suggest you’ve not removed it all and your cya is low.

CYA was at 60 last time I checked maybe 4-5 weeks ago and now it's more like 50. Since I failed the Overnight Chlorine Loss Test, I thought I'd try to deal with that problem before putting in more conditioner.

 

[Richard320]

CYA was at 60 last time I checked maybe 4-5 weeks ago and now it's more like 50. Since I failed the Overnight Chlorine Loss Test, I thought I'd try to deal with that problem before putting in more conditioner.

Exactly what I would recommend you do. SLAM is best done at 30-50 CYA level. Once it's over you rebalance the rest.

I would suggest you’ve not removed it all and your cya is low.

@Pool_Medic Why would he want to raise the CYA before he has finished the SLAM?

 

[Pool_Medic]

First, OP mentions water is clear, second he has not mentioned how long he slammed for and his cya is 30 ppm low for a swg.

 

[Red]

Not the results I was hoping for this morning: OCLT loss of 2.0

When	OCLT FC Loss
1st Night: Saturday - Sunday	3.0
2nd Night: Sunday - Monday	2.0
3rd Night: Monday - Tuesday	1.5
4th Night: Tuesday - Wednesday (today)	2.0

After @Richard320 recommended running water through other things, I did see my filter pressure go up by ~1.5 PSI yesterday, so maybe the chlorine found some gremlins in those pipes. I maybe only had the slide and the jets going for 60-90 minutes yesterday. Do I need to let those run for hours?

First, OP mentions water is clear, second he has not mentioned how long he slammed for and his cya is 30 ppm low for a swg.

I've SLAMed for 4 nights so far. My initial thought in going through chlorine was that my CYA was low, but I was out of reagent, out of town, and then we had some parties at the house, so I didn't get to looking at it again until this week. Even though I understand CYA stays in the water and isn't supposed to go down, historically, I have difficulty keeping it. I previously did evaporation tests for a different issue in 2017 and don't apparently have any leaks. My thought was to add more after I solve my current problem. Would more somehow be beneficial now? I know I lose some water from people playing in the pool, but I am surprised how quickly CYA goes down. At the beginning of April I added more conditioner and was at 100. After about 11 weeks, I'm down to 50. There was one party a week or so ago with a bunch of teenage boys and many waves. I lost at least 1" of water from that party.

----

I'm trying to figure out my next steps:

1. The one place I haven't tried cleaning that I can think of is behind the light. I think someone said it's okay to swim in the pool while FC is at SLAM levels. Is that correct? Maybe I need to hop in tonight and see if I can find anything there.
2. What about my Pentair GloBrites? I've never tried removing those. There's no niche, just conduit. Is there something I can/should try with those?
3. My filter pressure isn't high, but should I backwash it? I just cleaned it at the end of April, so the pressure isn't very high yet. My clean pressure was 11. It was a little above 14 until yesterday, and now it's around 16.
4. Should I run the slide and jets for a significantly longer time than I did yesterday?
5. Do I need to try higher chlorine levels?

Thanks for the help. It's appreciated.

 

[Mr Bruce]

1 Yes, remove the light. I can get mine out without getting in the water but it is harder. Ok to swim at SLAM levels though.
2 Not sure what those are.
3. Yes. Backwash when pressure rises 25% or in your case ~3psi
4. Probably? More chlorinated water circulating is a good thing.
5. No. SLAM level for your CYA is plenty. Any more is just wasted.

 

[Richard320]

Not the results I was hoping for this morning: OCLT loss of 2.0

When	OCLT FC Loss
1st Night: Saturday - Sunday	3.0
2nd Night: Sunday - Monday	2.0
3rd Night: Monday - Tuesday	1.5
4th Night: Tuesday - Wednesday (today)	2.0

After @Richard320 recommended running water through other things, I did see my filter pressure go up by ~1.5 PSI yesterday, so maybe the chlorine found some gremlins in those pipes. I maybe only had the slide and the jets going for 60-90 minutes yesterday. Do I need to let those run for hours?



I've SLAMed for 4 nights so far. My initial thought in going through chlorine was that my CYA was low, but I was out of reagent, out of town, and then we had some parties at the house, so I didn't get to looking at it again until this week. Even though I understand CYA stays in the water and isn't supposed to go down, historically, I have difficulty keeping it. I previously did evaporation tests for a different issue in 2017 and don't apparently have any leaks. My thought was to add more after I solve my current problem. Would more somehow be beneficial now? I know I lose some water from people playing in the pool, but I am surprised how quickly CYA goes down. At the beginning of April I added more conditioner and was at 100. After about 11 weeks, I'm down to 50. There was one party a week or so ago with a bunch of teenage boys and many waves. I lost at least 1" of water from that party.

----

I'm trying to figure out my next steps:

1. The one place I haven't tried cleaning that I can think of is behind the light. I think someone said it's okay to swim in the pool while FC is at SLAM levels. Is that correct? Maybe I need to hop in tonight and see if I can find anything there.
2. What about my Pentair GloBrites? I've never tried removing those. There's no niche, just conduit. Is there something I can/should try with those?
3. My filter pressure isn't high, but should I backwash it? I just cleaned it at the end of April, so the pressure isn't very high yet. My clean pressure was 11. It was a little above 14 until yesterday, and now it's around 16.
4. Should I run the slide and jets for a significantly longer time than I did yesterday?
5. Do I need to try higher chlorine levels?

Thanks for the help. It's appreciated.

1) Yes, get in and clean. keep the vacuum close by. See the pictures and you'll understand Think I may have found my FC demand issue?

2) I have no idea what those look like. Can't say,

3) You're overdue already. If clean is 11, backwash at 14.

4) There's no reservoir, just plumbing, so a couple hours a day should flush things out.

5) No, higher chlorine levels just burn off faster in the sun. Just stick with the chart.

 

[Red]

Thanks for your thoughts. I have cleaned out the light once before from in the pool. I haven't tried it from out of the pool.

I guess more important right now, if it's safe to swim at SLAM levels (FC 23 this morning), should I let the kids in? They're dying for a swim and some friends are coming over today.

 

[Mr Bruce]

If your CYA is 50 your FC is slightly above SLAM level (20). We always say that it's safe to swim at SLAM level or lower. If it is sunny there today it might drop to 20 by the time anyone wants to swim.

 

[Red]

If your CYA is 50 your FC is slightly above SLAM level (20). We always say that it's safe to swim at SLAM level or lower. If it is sunny there today it might drop to 20 by the time anyone wants to swim.

Thanks. I've been turning on SWG during the day. I turned it off. It will drop. I've been SLAMing at the CYA 60 level just because that dot test is sometimes frustrating to make sure you have it right.

 

[Red]

Last night I cleaned out behind the light. There was some black stuff. Whether it was algae or dirt, I don't know. It didn't seem slimy. A neighbor re-roofed a few months ago and I got a lot of very dark debris in the pool from that. What was behind the light may have been from that. Anyhow, the big light niche is clean now.

Another morning of a failed OCLT test

I didn't have time to backwash the filter last night, so hopefully I'll get home from work early enough tonight to do that.

 

[Richard320]

Last night I cleaned out behind the light. There was some black stuff. Whether it was algae or dirt, I don't know. It didn't seem slimy. A neighbor re-roofed a few months ago and I got a lot of very dark debris in the pool from that. What was behind the light may have been from that. Anyhow, the big light niche is clean now.

Another morning of a failed OCLT test

I didn't have time to backwash the filter last night, so hopefully I'll get home from work early enough tonight to do that.

Wash out your test vials really good. A couple people in the past had trouble because of residual test chemicals messing with their tests. A good scrubbing in the kitchen sink. It's a real long shot, but two minutes of washing dishes versus another 24 hours of SLAM is a good gamble.

 

[Red]

For the record, I backwashed the filter and cleaned out my vial, magnetic stirrer, and Sample Sizer several times. I also vacuumed out the pool filler chamber. The test chemicals were brand new.

I'm going to call my Overnight Chlorine Loss Test successful this morning, but I'm wondering about inconsistent test results....

My first test showed a 1.5 loss. I'm pretty desperate for this to be successful, so I ran the test again--from the same water sample. This time I showed a 3.0 loss. I was surprised to see such a difference. I thought maybe I didn't clean the vial well enough before the second test, so I should try again. I also grabbed a new water sample. Before the third test, I cleaned out the vial, et. al. extra well again. I also used a toothpick to clean out the DPD powder scoop. This time had a 1.0 loss. Hooray!

I wonder about some things:

• How much difference can a different water sample make? The pool had been circulating all night, so I assume it's pretty well blended. I took both samples from the Hayward Sense & Dispense unit. There's a valve on the sensor chamber where you can get samples.
• Some DPD powder always sticks to the scoop (although it was a brand new bottle/scoop last night). That could mean sometimes you end up with a little less DPD powder in the vial. Could that be making a difference? Maybe I need to scrape it out with a toothpick every time I test to make sure all the powder makes it in?

[edit: added comment about cleaning pool filler chamber]

 

[Richard320]

1.5 to 3 with the same sample tells me the problem is with the chemist.

The sample itself will be homogenous. So will the test chemical within the bottle. There's no contamination in the vial. That leaves the operator. In your eagerness/frustration you very likely squeezed the bottle which affects drop size and thus test results.

 

[JoeSelf]

This is why I have the Sample Sizer, consistent sample sizes. Bottle is upright and 1 drop per second. Drops should fall off the end, not jump off. Differing drop sizes matter too.