At my wits end - after 3 SLAMs

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So, just a quick update. Got home from work and water still looks pretty good (same as this morning). Except no more black soot in the skimmer. Really hard for me to determine if there is a problem. It's like trying to tell a difference between Sparkling clear and very clear.

FC=TC=9.0 tonight at 7:30pm

I will do another OCLT just to make sure in the morning.
 
run53 said:
I am trying to decide if that silt/slime in the picture I posted is sunscreen. How much sunscreen are we talking about to make a pool not sparkle? Like I said, probably only 2-3 bathers in the pool (although heavy sunscreen users) all last week and no one in the pool since Sunday. Yet just today, the sparkle was gone.
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My wife swims in our pool almost every day and the sunscreen she uses creates a film on the water that one can see. It has the water look less sparkly for sure. It generally dissipates so that it doesn't build up too much day to day, but that's just one person in a 16,000 gallon pool. Higher chlorine (FC/CYA ratio) levels helps some and faster circulation/filtration helps some.
 
FC reading this morning shows 7.5, so this indicates a failure of the OCLT.

Water still looks very clear(same as yesterday) but not sparkling.
Still perplexed as to why it passed the OCLT for 4 straight nights before it lost it's sparkle.

So it appears to be time for a proper SLAM to FC of 28. If you've been following this thread, you know that in my previous SLAMs I was using the wrong PoolCalculator, which told me to shock to 20ppm for my CYA levels. So, beware, there is a bad version of the PoolCalculator out there. Now that I have the corrected link, hopefully the 4th SLAM will be a charm to keep the water sparkling.

Another question....I usually leave my SWG on during the day when SLAMing. Then turn it off at night for the OCLT. I don't see any harm in doing this, but want to run it by the experts.
 
Leaving the SWG on during a SLAM is problematic. You have no real good idea of your FC consumption as it is constantly replenishing. The best way to SLAM and understand what's happening in your pool is to shut off the SWG and use liquid chlorine.
 
duraleigh said:
Leaving the SWG on during a SLAM is problematic. You have no real good idea of your FC consumption as it is constantly replenishing. The best way to SLAM and understand what's happening in your pool is to shut off the SWG and use liquid chlorine.
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OK thanks, will turn it off. Also, thinking that over shooting the shock target to maybe 30-32 just in case my CYA reading is off.
 
This sounds a litte madcap, but run the filter for the next 24 hours and tell us if the sparkle is back.

If so, just bump up your run time a little. If not, and there's more silt, investigate filter.

One other note...if you do have very mild iron staining and either your ph has been high or your metal sequestrant level has gotten low, its possible that what you're actually seeing is a very slight hint of yellow (iron) tint to your water, just enough to make it look different than usual.

In my own pool, I've gotten good at detecting that subtle hue change and top up the seqestrant.
 
Swampwoman said:
This sounds a litte madcap, but run the filter for the next 24 hours and tell us if the sparkle is back.

If so, just bump up your run time a little. If not, and there's more silt, investigate filter.

One other note...if you do have very mild iron staining and either your ph has been high or your metal sequestrant level has gotten low, its possible that what you're actually seeing is a very slight hint of yellow (iron) tint to your water, just enough to make it look different than usual.

In my own pool, I've gotten good at detecting that subtle hue change and top up the seqestrant.
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Thanks for the advice on the iron......I haven't done the ascorbic acid treatment yet so I'm not using my metal magic. I was saving it for when I do the treatment.

no more silt this morning, so that remains a mystery.

I will be sure to update this thread when the sparkle is back. I expect it to sparkle by this afternoon, as this is what happened in the previous 3 SLAMs (same day return to sparkle). I guess that's because I stay on top of it and never let it get too bad before I take action.

Although the OCLT failed (1.5ppm FC loss), I'm still not 100% sure that a SLAM is needed. I can't help thinking the margin of error on the OCLT could be at play here due to operator error or what have you. Also, some interesting points on iron and sunscreen that could "possibly" be taking the sparkle away. But in the end I guess the SLAM to proper levels can't hurt, since the previous SLAMs were too low on the shock level. So that's my plan.
 

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Well I started the slam about 2.5 hours ago and as expected, already the water is sparkling (unless my eyes are deceiving me). I will keep FC at 28 or more all day and then start the OCLT again tonight. Will keep you posted as I'm sure everyone can't wait to hear the results of that test tomorrow morning ;)
 
Got up early this morning to to check the OCLT (pump running all night with SWG off).

Last night at 8:30pm - TC=31, CC=0.5, FC=30.5

This morning at 6:00am - TC=30.0, CC=0.0, FC=30.0

Water is crystal clear (has been sparkling since 2 hours after the SLAM started yesterday).

We had some rain last night and this begs the question how that may affect the OCLT. If anything, I would think it would skew the results to lower the FC since more untreated water in the pool would dilute the FC. However, probably not enough rain to make a difference. Would love to hear opinions of rain affect on OCLT.

After the last 3 SLAMs that have passed all three tests (albeit at lower/incorrect FC shock levels), I am a bit cautious to declare success. However I think the ability to maintain the correct FC of 30 in the OCLT this time, is different. I am still debating keeping FC at 30 for one more day though and one more OCLT. Is this obsessive compulsive behavior?
 
duraleigh said:
Do you have ANY visible signs of algae?
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Not that I can see. I removed and checked behind the skimmer plates and return directors (where there was some during the last SLAM and I took a tooth brush to them).

The water looks fantastic. But it did after the last 3 SLAMs too. The real test will be when the FC drops below 9-10 again as that is when I've seen the sparkling go away. Still very clear, just doesn't sparkle like it is now. I would think I should be able to drop to an FC of 3-5 as that is what PoolMath suggests for CYA=70 and SWG.
 
I would think I should be able to drop to an FC of 3-5 as that is what PoolMath suggests for CYA=70 and SWG.
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I agree. I can't explain your past issues but perhaps this time it will work. Water is water, algae is algae and, used properly, chlorine kills all of it
 
I’m kind of new to this forum But since I’ve joined it’s the first time in ten years I feel I have control of my pool chemistry and the term Trouble Free is a great description. So I’ve been reading this post this is kind of how I see it if I’m correct this is the 4th slam. Now I’ve read other post about marathon slams, so at what point do you take into account the cost of chemicals for the slam, frustration and then the lost time spent in the pool due to unhealthy chlorine levels. So when do you ask yourself would it be better to drain the pool and start fresh? Just curious when replacing the water is an option.
 
run53 said:
I am leaning that way for sure.....except, why does it turn crystal clear during each of the 3 SLAMs? If it were filtration, why would the SLAM make it sparkling?

By the way, having this forum to walk me through the trouble shooting is great. I really appreciate all the dialogue and ideas.

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Hmmm...interesting. Lot's of sunscreen last week as we were on vacation. Maybe 2 or 3 bathers for short periods of time during vacation. No one has been in the pool since Sunday though. The water sparkled until this morning.

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I test at 8:00pm (pump is off) and again at 7:00am (before the pump turns on), I run the pump from 7:30am to 7:30pm
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run53 said:
I am trying to decide if that silt/slime in the picture I posted is sunscreen. How much sunscreen are we talking about to make a pool not sparkle? Like I said, probably only 2-3 bathers in the pool (although heavy sunscreen users) all last week and no one in the pool since Sunday. Yet just today, the sparkle was gone.
Click to expand...

I've seen that black stuff appear in my pool after having just one guest swimmer with sunscreen. Fortunately 99% of the time it's just the two of us with no sunscreen so I don't have to deal with it very often.

I was going to ask if you tried running your pump/filter (SWCG off) overnight when doing the OCLT, but I see you recently did that.

I had a situation where I would pass the OCLT with the pump off overnight (like normal) but would fail if I ran the system overnight. Turned out something in the filter was eating FC. Conducting the SLAM with the system running 24/7 (SWCG off) resolved the problem.

Are you running your system 24/7 during the SLAM?
 
Run53 - Earlier you said "I would think I should be able to drop to an FC of 3-5 as that is what PoolMath suggests for CYA=70 and SWG." Although that is true, I think in your case you might want to target a little higher. I have read a number of folks targeting in the 7-8 range, just so they don't run into trouble. As long as you are under, let's say 15, you are fine. Really, as long as you aren't over 28, you are okay. I just wanted to give some extra margin to work with...
 
Saturn94 said:
I've seen that black stuff appear in my pool after having just one guest swimmer with sunscreen. Fortunately 99% of the time it's just the two of us with no sunscreen so I don't have to deal with it very often.

I was going to ask if you tried running your pump/filter (SWCG off) overnight when doing the OCLT, but I see you recently did that.

I had a situation where I would pass the OCLT with the pump off overnight (like normal) but would fail if I ran the system overnight. Turned out something in the filter was eating FC. Conducting the SLAM with the system running 24/7 (SWCG off) resolved the problem.

Are you running your system 24/7 during the SLAM?
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Yes, this time I am running it 24/7 although I hadn't always done that in the past. I am also going to clean my filter and recharge the DE, just in case something in there.

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pabeader said:
Run53 - Earlier you said "I would think I should be able to drop to an FC of 3-5 as that is what PoolMath suggests for CYA=70 and SWG." Although that is true, I think in your case you might want to target a little higher. I have read a number of folks targeting in the 7-8 range, just so they don't run into trouble. As long as you are under, let's say 15, you are fine. Really, as long as you aren't over 28, you are okay. I just wanted to give some extra margin to work with...
Click to expand...

I agree. 7-8 is probably a good range for my pool just to be safe
 

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