No CYA, Foggy Pool

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PoolOnB

0
Feb 13, 2016
34
Boston, MA
Pool has been open for three weeks. First two weeks, everything was very well balanced, chemicals holding, and water crystal clear. We had been running pump 24/7 during this time. At the start of week 3 (last Friday night) we turned the pump timer on, which turns the pump off overnight. We woke the next day to a very foggy pool. It got a little better as the week went on (resumed running it 24/7), but is even worse this morning. Last night we ran pool math and added 1.5 gallons of shock. This morning, our chlorine is low again.

This morning's readings are:

FC 0.5
CC 2.5
TC 3.5
CYA 0
Ph 7.2
TA 100
CH 100
72 degrees
Extremely cloudy; can't see bottom of deep end.

Last year we had consistently very high CYA (we converted from baquacil to chlorine last June), so we're gun shy on adding too much, but clearly we need to get over that. I think we are not done shocking the pool, but want to get some input before we do anything more.
 
If you had high CYA last year, you did not drain the pool to remove it, you have high CC now with high FC demand, you most likely have ammonia.

You potentially will need lots of bleach/liquid chlorine.

The process is:
Add chlorine to get to FC of 10. Be sure pump is running. Wait 15 minutes, Test. If FC less than 6, redose to FC 10. Repeat. As soon as your FC holds above 6, go to a regular SLAM. DO NOT add any CYA until the ammonia eradication process is complete.

If you wish, you can go to a store that sells aquariums and get an ammonia test. Whatever ppm ammonia the test shows, multiply it by 10 and that will be approximately the total FC ppm you will need to add to get rid of the ammonia. But you cannot add it all at once. You must follow the above process.

Good Luck
 
I concur with mknauss.

Whether it's ammonia or something else, you need to kill it with bleach. Lots of bleach. When it starts holding -- it could be the first time, you might have already gotten ahead of it a little -- then add some CYA to about 30 and follow the SLAM instructions. Shock Level And Maintain. That M is the killer.

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Let's slow down here a minute. What were your CYA & FC levels over the two weeks that you say "everything was very well balanced, chemicals holding"

Ammonia conversion doesn't happen overnight. If the pool was holding CYA & FC for two weeks it is most likely not ammonia.
 
No fizzing at all when we add liquid chlorine.

We did drain about a third last year mid summer. It helped, but we still had high CYA nearly all summer. We closed the pool, draining the appropriate amount (below intakes), but when we opened the pool this year we actually had so much snow and rain water in the pool we had to drain down more. Meaning, I do think that last year's water potentially has been diluted quite a bit between our draining/refilling in late July and with the off-season rain and snow water.

Here is our chem log from the last few weeks:

June 1 (first test after the initial opening, vacuum, brushing, etc. - water was crystal clear beginning now):
FC 3.5
CC 0.5
TC 4.0
Ph 7.2
CYA 45
TA 110
CH - did not test
Temp:68

June 4:
FC 0.5
CC 0.0
TC 0.5
Ph 7.6
CYA 37.5
TA 100
CH - did not test
Temp:68
Water still crystal clear

We turned the pump off night of June 10.

June 11 (8 AM; woke up to foggy pool; couldn't see deep end bottom):
FC 0.0
CC 0.0
TC 0.0
Ph 7.2
CYA 32
TA 90
CH - did not test
Temp:69

June 11 (PM - after adding morning chemicals per pool math; prior to running these numbers, we noticed the pool got clearer as day went on, but still foggy):
FC 4.0
CC 0.5
TC 4.5
Ph 7.4
CYA 35
TA 80
CH - 100
Temp:70

June 16 (last evening's test; added 1.5 gal chlorine per pool math):
FC 0
CC 0
TC 0
Ph 7.2
CYA 0
TA 90
CH - 125
Temp: 70
Extremely foggy; cannot see bottom at all

June 17 (this morning's test, already reported above):
FC 0.5
CC 2.5
TC 3.5
CYA 0
Ph 7.2
TA 100
CH 100
72 degrees
Extremely cloudy; can't see bottom at all

Thank you very much for your insights.
 
I assume you are doing your own testing?
How did the CYA go from 30's prior to June 16 to ZERO. Any water exchange?
Something is odd -----------
 
Two other notes:

Prior to June 11 (maybe the 7th or 8th):
- after back washing a little too much, we added water from the hose. It was more or less a top off - a couple inches of water at the most.
- DE was accidentally dropped into the pool directly. It settled at the bottom of the shallow end and we vacuumed it up. Not sure if this is material, but worth mentioning I suppose.

My CYA tube has a 30 and 40 line. It was 3/4 between the two, hence 37.5.

EDITED: It has also rained A LOT by Boston standards in the last 2 weeks. I don't think enough to cause a true 'water exchange' event, but it has been a material amount of rain. That's about all I can think of...
 
First, I was unaware that there are two 3" chlorinating tablets in my skimmer (husband added those yesterday). Those are still in the skimmer as of right now. Just tested the chlorine and it is:

FC 1.5
CC 2.0
TC 3.5

Should those be removed so we can isolate what's going on here?

We went to the pet store and picked up an ammonia test kit. We tested the water twice, and both times the reading was 0.5 ppm.

The water is not as foggy as it was earlier. Yesterday through this afternoon we couldn't see the bottom anywhere in the pool. Just now, while testing the ammonia, we could see the bottom in the shallow end and down about half way of the decline into the deep end.

Any advice about how to proceed is much appreciated. Thank you!


PS: I've been reading lots of other threads for my own education today. I now understand that the CYA cylinder is not intended for readings between the markings, so I will adjust the way we're testing it going forward.

EDIT at 9:02pm: I just found my test results from the day we opened (5/29). We opened the pool to 0 CYA. CYA was added (don't know exact amount, but it was small as we were extremely gun shy to add more after last summer's issues), which is likely what took it up to the 45 that I reported in the June 1 test.
 
Last edited:

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I'm pretty certain you are experiencing a bacterial bloom (cloudy pool). The bacteria causing the bloom is converting your CYA to ammonia (your ammonia test results = positive). I would remove the pucks and follow mknauss initial post! DO NOT add CYA! CYA is essentially food for the bacteria.
 
mknauss said:
If you had high CYA last year, you did not drain the pool to remove it, you have high CC now with high FC demand, you most likely have ammonia.

You potentially will need lots of bleach/liquid chlorine.

The process is:
Add chlorine to get to FC of 10. Be sure pump is running. Wait 15 minutes, Test. If FC less than 6, redose to FC 10. Repeat. As soon as your FC holds above 6, go to a regular SLAM. DO NOT add any CYA until the ammonia eradication process is complete.

If you wish, you can go to a store that sells aquariums and get an ammonia test. Whatever ppm ammonia the test shows, multiply it by 10 and that will be approximately the total FC ppm you will need to add to get rid of the ammonia. But you cannot add it all at once. You must follow the above process.

Good Luck
Click to expand...


I ran the first part of this so far this morning (first removing the chlorine pucks). I am holding north of a 6 FC (I'm at 7). Now it's time to SLAM. I want to make sure I'm doing this right, though.

When SLAMing, with 0 CYA, using Pool Math calculator, I am "solving" to a 10 FC. Adding the appropriate amount of liquid chlorine, and then rinse/repeat not more than 1x/hour, but more than 2x/day. And then stopping when I hit the criteria outlined on the SLAM page of TFP?

Appreciate the help!
 
Good to hear on the ammonia.

Part of the SLAM is adjusting your pH and placing enough CYA powder in a sock hanging in front of a pool return to get to CYA of 30ppm. You assume the CYA is in the pool and use a shock level of 12ppm FC.

Test / dose as often as you can to start. Try to do it at least 4x per day once your FC is holding better.
Once your water is crystal clear, then do an OCLT to check if you have killed all the algae.

Have fun!
 
PoolOnB said:
Can you give me more detail on the CYA in a sock comment?

Ph is 7.2 (as of last night)
CYA remains 0.

I thought the instructions were not to add any CYA.
Click to expand...
Without any CYA, your bleach will be destroyed by the sun before it can destroy any algae. You held 6 FC overnight, so whatever was killing the CYA is now dead. Now it's safe to add more, to a target of 30.

The CYA bottles will tell you to either scatter it in the pool or pour it down the skimmer. Neither idea is very good. On the floor, you may end up with white freckles. In the skimmer, it all collects in the filter and if you need to backwash before it all dissolves and it goes down the drain. So you pour it into a hole-less sock or nylon and tied it shut and set that in the skimmer or dangle it in front of a return jet. You want a lot of water flow to speed up the dissolving. If you stop and knead the sock every so often, it will dissolve even faster.
 
I actually did not hold FC 6 overnight. I didn't add any liquid chlorine last night as I was waiting for a response. Last FC read last night was 1.5 (8:23pm).

I started measuring in 15 min increments and adding based on pool math calculator to get to a 10. Here are my FC logs for today:

9:05am - FC 1.5 (added liquid chlorine to get to FC 10)
9:20am - FC 1.5 (added liquid chlorine to get to FC 10)
9:40 am - FC 7 (didn't add, because I held above 6)
9:54 am - FC 5.5 (added again to get to 10)
just now, 10:11 am - FC 9.5 (I think I'm ready to start SLAMing...?)
 
PoolOnB said:
I actually did not hold FC 6 overnight. I didn't add any liquid chlorine last night as I was waiting for a response. Last FC read last night was 1.5 (8:23pm).

I started measuring in 15 min increments and adding based on pool math calculator to get to a 10. Here are my FC logs for today:

9:05am - FC 1.5 (added liquid chlorine to get to FC 10)
9:20am - FC 1.5 (added liquid chlorine to get to FC 10)
9:40 am - FC 7 (didn't add, because I held above 6)
9:54 am - FC 5.5 (added again to get to 10)
just now, 10:11 am - FC 9.5 (I think I'm ready to start SLAMing...?)
Click to expand...
Yes. And actually, you have been already.
 
I apologize for all the questions.. but you're extremely helpful!!

For FC, although I have 0 CYA at the moment, I am using the chart and assuming I have a CYA 30, therefore solving to FC 12.

For CYA, do I add that in a sock/nylon before adding any chlorine, or is that done at the same time as the initial chlorine add? And, am I right in adding enough CYA to get to a 30 from my current 0?
 
PoolOnB said:
I apologize for all the questions.. but you're extremely helpful!!

For FC, although I have 0 CYA at the moment, I am using the chart and assuming I have a CYA 30, therefore solving to FC 12.

For CYA, do I add that in a sock/nylon before adding any chlorine, or is that done at the same time as the initial chlorine add? And, am I right in adding enough CYA to get to a 30 from my current 0?
Click to expand...
Same time. Shock to 10 FC. Mess with CYA. Next time around, shock to 10 or 12, depending on how long the CYA has been in there and how much is left in the sock. After that, shock level is 12. Give the sock a squeeze now and then after it gets soggy and it will dissolve a lot faster.
 
To get my CYA from 0 to 30, I'm being told to add 88 oz by weight. That's a whole lot of CYA. As mentioned earlier, I'm very gun-shy of adding CYA after last year's issues. Just confirming this sounds correct.

I will also shock to FC 10 per your last instructions.
 

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