pool consuming bleach - water clear

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D

da5487

0
Sep 23, 2015
11
Chicago area, IL
Hey community,
My pool was opened three weeks ago. Things have seemed to go well so far with the method, I began managing my own chemicals last year using this site.

Here are a few recent measurements (Taylor K-2006c kit)

FC (variable)
CC 0.2
pH 7.5
ALK 90
CH 280
CYA 50
water: clear
pool: gets a bit dirty each day - windy here and lots of plant/tree stuff/debris blowing around

Last weekend, I started noticing chlorine consumption around 4-6 ppm per day. For reference, at the end of last season I was putting about 2 ppm from bleach into the pool each night.

Thinking the 4-6 ppm consumption was high and was trending higher, I decided to shock the pool two days ago. I brought FC up to 22. By the end of the next day, it was below 10. So, I added more chlorine (8.25% bleach) last night to about 23. This morning, it was 22. At mid-morning today, it was 18, and by 1:30 pm it was 10. The water is still clear. There is a smell, chloramines?, and has been for these few weeks.

Isn't this level of FC consumption unusual? Should I shock and hold again tonight? This morning I did not add more FC to hold 20+ because I thought it held to a 1 ppm loss over night. The pool is on the south side of the house, is in full sun all day, but I do have CYA at 50.

any insights will be appreciated. thanks
 
You are correct! It is time to SLAM and hold it there until you pass all 3 SLAM criteria (link below). Any FC loss over 4 is alarming, and the smells are probably from the excessive CCs oxidizing. Your pool has a fever, and the only prescription is ...... :) SLAM!
 
Would that have helped me avoid this? I can't figure out what is brewing in the pool and why.
Click to expand...
No, no help from the Nature2....you should let it go. I am not sure what it is, either, but it is really important to understand the solution.....the SLAM process.

You are burning up a lot of FC playing p[atty-cake with the organics in your pool.

SLAM them out of there and your pool will turn to normal consumption.
 
+1 on Slam=solution

In addition to the usual organic suspects like nascent algae, there are also occasional chemical reactions that may fight FC...have you added anything other than straight liquid chlorine?

When you opened, did you pump off any antifreeze in the lines? RV antifreeze is harmless but we've seen a few cases where if a larger amount goes into the pool sometimes the chlorine demand will spike while oxidizing it, or so the theory went last year on a few threads ;)
 
Swampwoman said:
+1 on Slam=solution

In addition to the usual organic suspects like nascent algae, there are also occasional chemical reactions that may fight FC...have you added anything other than straight liquid chlorine?

When you opened, did you pump off any antifreeze in the lines? RV antifreeze is harmless but we've seen a few cases where if a larger amount goes into the pool sometimes the chlorine demand will spike while oxidizing it, or so the theory went last year on a few threads ;)
Click to expand...

I opened the skimmers after the pool co. left because I had to get the water level up. They pumped antifreeze out of those, but I did notice a brief flash of pink when I opened those skimmers. That was three weeks ago, think that was enough? Another thought is that my lawn service might have let some fertilizer pellets get into the pool?? I noticed a small amount on the deck a week ago after a treatment. Or, we had a week straight of rain last week, some pretty heavy. Perhaps all three factors contribute. I am holding FC above shock level for one day now and counting, will see how it goes. thanks for the feedback!
 
update:

you can see in my notes below I am battling a chlorine guzzling monster (that is hiding in clear water)

is this what SLAMing is like? I'm not sure I trust these CC numbers


datetimeFCCC
26-May7:50 PM33shocked > 20
26-May9:00 PM32two hours later still holding
26-May11:00 PM330.4still in evening - holding and CC < 0.5
27-May6:45 AM280.6morning - lost 5 ppm
27-May9:00 AM242 hours later - down 4 more
27-May9:05 AM29added 5 FC
27-May11:15 AM230.3two hours - lost 6
27-May11:20 AM33added 10 FC
27-May1:00 PM230.5two hours - lost 10 ??? - or sunlight ate away what I poured in?
27-May1:05 AM33added 10 FC
27-May2:00 PM310.6one hour after add - only lost two
27-May3:30 PM2512.5 hours after add - down 8
27-May3:35 AM30added 5 FC

thoughts? am I feeding a CC generation cycle by putting more FC in? It seems like CC is growing, not getting better.
 
You should measure at dusk, top off, measure again, then first thing in the morning. to see what your overnight lost is. (Shouldn't be any unless its fighting algae) During the daylight hours, sunlight breaks down chlorine even with a CYA of 50. Looking at your 5/26 11pm and 5/27 the drop of 5 tells me something is consuming the chlorine.
 

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bobodaclown said:
You should measure at dusk, top off, measure again, then first thing in the morning. to see what your overnight lost is. (Shouldn't be any unless its fighting algae) During the daylight hours, sunlight breaks down chlorine even with a CYA of 50. Looking at your 5/26 11pm and 5/27 the drop of 5 tells me something is consuming the chlorine.
Click to expand...

yes, I agree, thanks. I double checked just now using a 10 ml sample (0.5 ppm resolution) - got what I expected given I added 5 an hour ago - it held at that value for an hour. And, the CC was 0.5 CC or less. Barely any pink when I added the indicator. So, my CC numbers in the table above are suspect. I am fairly confident I am < 0.5 ppm CC. (I was using a 1 part in 4 diluted sample with distilled water and my LaMotte ColorQ kit - I know, duck for cover).
 
Just to recap:
1. Keep slamming
2. As you add bleach, it kills stuff and oxidizes stuff, and then when it is used up retires as smelly CC. It waits for the sun to burn it off. So, until you win this SLAM CC will cycle between 0-2 many times a day. You can skip testing CC until FC holds IMO. Unless you are curious and enjoy seeing it.
3. Nothing can eat bleach infinitely, so keep testing and bringing back to shock. Be sure to brush in case it is on the walls or floor. Is there a built in light?
 
This is an interesting thread, subscribing. Being this is my first year owning my pool and opening my pool I have had some reservations about whether or not I SLAMed it properly. Not to hijack your thread but I was under the assumption that the shock FC level was where you wanted to be. Never thought about going over the Shock FC level. I have an issue, either my gallons calculation is not correct or the chlorine im using is not 13.3% like is states. I always added the amount the pool calculator stated to add to bring it to shock level and I would check it after and it would always be lower then what it should be. Next time I shock Im going to bring it up above the shock FC so I know its at shock level and then do an overnight test. The last overnight test I did before letting the FC drop to target level it dropped 1ppm over night so I let it drop. Maybe Ill perform an over night test tonight just to make sure everything is good. My pool has been dropping from 7ppm to 4-5ppm everyday. I add chlorine at night and dont test again until the next night. CYA is about 55 and it gets a lot of direct sunlight.
 
Spoolin98 said:
This is an interesting thread, subscribing. Being this is my first year owning my pool and opening my pool I have had some reservations about whether or not I SLAMed it properly. Not to hijack your thread but I was under the assumption that the shock FC level was where you wanted to be. Never thought about going over the Shock FC level. I have an issue, either my gallons calculation is not correct or the chlorine im using is not 13.3% like is states. I always added the amount the pool calculator stated to add to bring it to shock level and I would check it after and it would always be lower then what it should be. Next time I shock Im going to bring it up above the shock FC so I know its at shock level and then do an overnight test. The last overnight test I did before letting the FC drop to target level it dropped 1ppm over night so I let it drop. Maybe Ill perform an over night test tonight just to make sure everything is good. My pool has been dropping from 7ppm to 4-5ppm everyday. I add chlorine at night and dont test again until the next night. CYA is about 55 and it gets a lot of direct sunlight.
Click to expand...

Yes, the shock FC is where you want to be when SLAMing. Chlorine % in the bottle degrades over time. This happens faster at higher concentrations and if it's stored improperly (too hot, or in direct sunlight). It's very possible your 13.3% chlorine has degraded slightly.

An FC loss of 2-4ppm per day is normal.
 
No, that is not a normal SLAM. Either there is more pink antifreeze than originally thought or there is bacteria consuming your CYA and converting it to ammonia. Either way the answer is keep adding chlorine until it holds. When it does hold, retest your CYA to see if it is gone. Is the pump running the whole time? Weird how consumption fluctuates.
 
Da, thanks for posting your tests. I'm with Dave in that it has the mystery chem battle feel...but either way, oxidization is key and the way forward so I'm just chiming in for moral support ;)

However, I also want to note that at such high levels (eg 33) drops in FC also "look" huge, but in fact, losing 10 ppm from 33 is actually only 30% - still fast in two hours, but that would be a normal-to-low loss over a sunny day.

While your ccs are going up, they're also still lower than the weird chem effects of a few battles last year, where the ccs were really pronounce and all over the place (2, 5, 1, then 7 etc.) I hope that means you're close ;)

Just out of curiosity, when you had the pool guys open, did you tell them it was a "no CHEMS" opening, or did they balance?

I use techs to open mine each year too (as my old solid cover is just a bit heavy for me) and if I don't stop them they'll add enzymes and other mystery compounds.

But your combo theory makes sense to me. Lets see what an OCLT brings, a cya test, and if the drops in FC grow less pronounced over another day.

It might help to run a little closer to slam level if the water remains clear etc. eg for 50 cya, your Slam value is 20, so see how long 24 takes to drop to 20... Don't want you to waste chlorine or nuke the pool ;)
 
Swampwoman said:
Da, thanks for posting your tests. I'm with Dave in that it has the mystery chem battle feel...but either way, oxidization is key and the way forward so I'm just chiming in for moral support ;)

However, I also want to note that at such high levels (eg 33) drops in FC also "look" huge, but in fact, losing 10 ppm from 33 is actually only 30% - still fast in two hours, but that would be a normal-to-low loss over a sunny day.

While your ccs are going up, they're also still lower than the weird chem effects of a few battles last year, where the ccs were really pronounce and all over the place (2, 5, 1, then 7 etc.) I hope that means you're close ;)

Just out of curiosity, when you had the pool guys open, did you tell them it was a "no CHEMS" opening, or did they balance?

I use techs to open mine each year too (as my old solid cover is just a bit heavy for me) and if I don't stop them they'll add enzymes and other mystery compounds.

But your combo theory makes sense to me. Lets see what an OCLT brings, a cya test, and if the drops in FC grow less pronounced over another day.

It might help to run a little closer to slam level if the water remains clear etc. eg for 50 cya, your Slam value is 20, so see how long 24 takes to drop to 20... Don't want you to waste chlorine or nuke the pool ;)
Click to expand...


Thanks for the support! Here is an update:
topped off and checked last night (water clear as it has been all along)
10:40 pm FC 31
this morning
5:45 am FC 30 CC < 0.5 (no pink with indicator)
10:20 am FC 23 CYA 47 CC < 0.5
11:40 am FC 20

So, I had 1 ppm drop over night, water is clear, CC < 0.5.
I'm thinking of letting it drift down from here, should I hover it around 20 one more day/night?
As to some of the other speculations and questions:
I opened "No Chem", I balanced, although they did put a bottle of algaecide in there. The pool was slightly green, lots of leaves and debris in there under the cover, and the water cleared up within a day.
Last season, but not this year, there was a Nature2 cartridge.
Last year mid-summer I tried that CYA reducer (because I was at 150). That did not work, I wound up doing partial drain+fills to get CYA to below 60.
There has also been phos-free (last season) and clarifier (last season or season prior). Other? bird droppings, acid rain, lots of spring blossom debris, we get the occasional frog or turtle from nearby pond.

thanks for all the feedback and questions!
 
If I understand correctly, at CYA 47, rounded to 50, any FC over 20 will be poorly protected from the sun. I believe it to be a waste to exceed your shock level of 20, with the potential exception of a 2-4ppm extra if you will be unable to add the next day. Your higher than desired loses may be partially because you are exceeding your current CYA protection by so much.
 
Da, you will always lose FC during the sun, and at higher FC rates it will look like more than when lower ;) So let the OCLT be your guide -- you were really close but I'd do one more tonight to confirm, then let it drift down and see if your normal consumption rate returns.
 

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