Trouble Maintaining Chlorine and Stabilizer

[Bperry]

How long do I need to wait after adding chlorine to test? Don’t I need to wait for it to mix with the pool water for a little while to get an accurate reading? I am just going off of the pole volume number given to me by the builder. From what I read, PH testing is probably not accurate right now during the SLAM process? I did some simple math based off my pool dimensions and average depth and it appears that 11.7k gallons is in the ballpark, at least.

Autofill has been off for about a week now. No change in water level. Will leave it off.

Just loaded up with 10 gallons of liquid chlorine, so I think I am set for a while now . I am going to up my FC target to 12 to stay on the safe side

If you keep the pump running, 30 minutes should be enough. That fact that you consistent never hit your target indicates something is off. Is the chlorine % correct in poolmath?

 

[xxkylexx]

If you keep the pump running, 30 minutes should be enough. That fact that you consistent never hit your target indicates something is off. Is the chlorine % correct in poolmath?

Yes, bottle shows 10.5%, which I set in pool math. I just tested again after 1hr 10 mins and had a 3ppm loss (9 when the previous target was 12). I will test again after 30 mins this time (in 15 mins).

 

[xxkylexx]

I just noticed that the bottle actually says “provides 10% available chlorine”, so I will adjust the pool math to that, but I don’t think 0.5% will make a big difference.

 

[xxkylexx]

After correcting 30 minutes ago to go from FC 9 -> 12, I am now reading FC 10. It is cloudy out today so I don't think the sun is beating down too hard on the pool. I am adding 3.75 cups to try to go from FC 10 to 12 now.

 

[Bperry]

After correcting 30 minutes ago to go from FC 9 -> 12, I am now reading FC 10. It is cloudy out today so I don't think the sun is beating down too hard on the pool. I am adding 3.75 cups to try to go from FC 10 to 12 now.

View attachment 382659

You have something eating chlorine it seems.

 

[xxkylexx]

You have something eating chlorine it seems.

Indeed. Should I turn the SWG back on to 100% to help maintain FC levels during the SLAM?

 

[Bperry]

Indeed. Should I turn the SWG back on to 100% to help maintain FC levels during the SLAM?

Generally the recommendation is to keep it off so you can keep track of what went in the water.

Is the pool covered? Keep the cover off if so. Will need someone with more expertise to advise further, but if I had to guess it would be to keep the slam going.

 

[xxkylexx]

Generally the recommendation is to keep it off so you can keep track of what went in the water.

Is the pool covered? Keep the cover off if so. Will need someone with more expertise to advise further, but if I had to guess it would be to keep the slam going.

The pool is not covered. Just has a screen enclosure around it.

I read the following in the pool school article on SWGs, which is why I thought it might be helpful to have it on.

SWGs are not good at SLAMing (or shocking) the pool because SLAMing depends on the FC level going up quickly and a SWG only adds chlorine slowly. If you are SLAMing the pool you should add chlorine manually. A SWG can be used to help maintain the FC level during SLAMing, but the initial addition of chlorine to shock level should always be done manually.

It is my understanding that all we're trying to do here is keep the FC level up above the SLAM target, so the SWG might not hurt and help conserve some of the liquid chlorine that I have in stock. As long as I continue testing and adding liquid chlorine to stay at SLAM targets.

 

[jmastron]

After correcting 30 minutes ago to go from FC 9 -> 12, I am now reading FC 10. It is cloudy out today so I don't think the sun is beating down too hard on the pool. I am adding 3.75 cups to try to go from FC 10 to 12 now.

View attachment 382659

Just to be clear, did you test that it was at 12ppm at some point, or do you mean you were at 9, added, and 30 minutes later measured 10? If the latter, it's possible your liquid chlorine is not full strength, which could happen if it's old or was stored in a hot place.

BTW, I wouldn't keep the chlorine and acid near each other (you may have just done that for the picture). Both generally have vented caps and you really don't want the fumes mixing, or worse something knocking them over.

 

[xxkylexx]

Just to be clear, did you test that it was at 12ppm at some point, or do you mean you were at 9, added, and 30 minutes later measured 10? If the latter, it's possible your liquid chlorine is not full strength, which could happen if it's old or was stored in a hot place.

BTW, I wouldn't keep the chlorine and acid near each other (you may have just done that for the picture). Both generally have vented caps and you really don't want the fumes mixing, or worse something knocking them over.

I tested it at 9 and my target was 12, which I put into Pool Math and adjusted for. 30 mins later the FC reading was 10. It's entirely possible that this chlorine isn't full strength. I wouldn't think it was old, having bought it from a pool store where they sell this stuff all day long to people, but who knows?

Thanks for the tips.

 

[Bperry]

The pool is not covered. Just has a screen enclosure around it.

I read the following in the pool school article on SWGs, which is why I thought it might be helpful to have it on.



It is my understanding that all we're trying to do here is keep the FC level up above the SLAM target, so the SWG might not hurt and help conserve some of the liquid chlorine that I have in stock. As long as I continue testing and adding liquid chlorine to stay at SLAM targets.

It’s probably ok, as long as you are not calculating how much you lose accurately. Since you seem to be losing lots of it, it might be good to keep it off and carefully track how much chlorine is being added so that you know when things settle down.

Your SWG has a finite life and you don’t want to use it all up fighting a chlorine battle when you’re already having to be out there manually adding bleach. That’s just my opinion though.

 

[jmastron]

I tested it at 9 and my target was 12, which I put into Pool Math and adjusted for. 30 mins later the FC reading was 10. It's entirely possible that this chlorine isn't full strength. I wouldn't think it was old, having bought it from a pool store where they sell this stuff all day long to people, but who knows?

Thanks for the tips.

I think if something aggressive were really consuming 2+ ppm in 30 minutes, it wouldn't still be at 9 however many hours after you last added; it'd be at 0 within 6 hours. Maybe after one addition try testing every 30 minutes over a couple hours -- then we'll see the actual consumption rate, which would be very helpful.

With all the shortages over the summer high demand, I wouldn't be surprised if stores started getting more than they needed a few months ago and are rotating out the oldest (yes, I'm one who digs back for newer milk at the grocery store . Or what they got in was lower than spec for whatever reason. Is there a date code? Is there somewhere else you could get a few gallons of a different brand to compare?

And I agree with not using the SWCG, just to able to keep it simpler to track of what you're putting in and the results, especially to be able to determine overnight and during-day losses which are the key indicators of progress.

Typically here we do test then calculate approximate amounts of chemicals to add, but we don't assume the result; we test for that too. So, for example, an overnight chlorine loss test means the difference from the test you do 30 minutes (or more) after adding chlorine to the test you do in the morning, not having added any in between.

 

[xxkylexx]

Did a true overnight loss test last night. Tested my water just before bed @ 11pm and had FC of 12.5 (I had added some liquid chlorine about 30 mins prior). Checked this morning at 6am (I have little kids, so no sleeping in here ) and FC is at 8.5. So we lost 4ppm of FC over 7 hours.

 

[xxkylexx]

With all the shortages over the summer high demand, I wouldn't be surprised if stores started getting more than they needed a few months ago and are rotating out the oldest (yes, I'm one who digs back for newer milk at the grocery store . Or what they got in was lower than spec for whatever reason. Is there a date code? Is there somewhere else you could get a few gallons of a different brand to compare?

I can't find a date code. I'll see if I can get some from Home Depot to compare with, but I am pretty loaded with this pool store stuff for a while.

 

[TampaKathy]

I can't find a date code. I'll see if I can get some from Home Depot to compare with, but I am pretty loaded with this pool store stuff for a while.

Are there any stamps on the bottle? It might not be obvious that it's a date code. This article talks about it. I didn't see Pinch a Penny listed but this should give you an idea.
Chlorine Date Code Decoder - Further Reading

 

[xxkylexx]

Are there any stamps on the bottle? It might not be obvious that it's a date code. This article talks about it. I didn't see Pinch a Penny listed but this should give you an idea.
Chlorine Date Code Decoder - Further Reading

I found this stamped on the bottom on the bottles. Seems like it might be a date code for 09/21?

 

[Turbo1Ton]

I doubt that code is for the fill. Most likely for the manufacture of the bottle. Usually it would printed on in ink. Any printing on the bottle at all?

--Jeff

 

[xxkylexx]

I doubt that code is for the fill. Most likely for the manufacture of the bottle. Usually it would printed on in ink. Any printing on the bottle at all?

--Jeff

None that I can find. Well at least we know it is on or sometime after 09/21 then Would that he considered “old”?

 

[Turbo1Ton]

I would suspect the same as you! Not terribly old, no. Would think it would still be full strength.

--Jeff

 

[proavia]

Are these refillable jugs? If so, no telling how old the chlorine really is.
Usually, disposable bottles have a date code stamped on the bottle, label or box in ink.
It could be old stock or your pool capacity (11.7k) is off.