My CYA went to 0...

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Cloey123

0
May 22, 2014
27
Clinton, Mississippi
I purchased my house at the beginning of the summer last year and my CYA was around 220. I did several partial drains and got it down to 50. Since it was at 50 last summer and i only use liquid bleach as my chlorine I have assumed it was still 50. I have only tested my FC a few times this year and have been adding the same amount of chlorine every night that I did last year and it has been staying crystal clear. This weekend I noticed it was a bit dull so I tested FC and it was 0 so I began a SLAM based on CYA of 50. I got my FC up to 20 and it was going away really fast during the bright hot day (95 - 99 degree in full sun). After the first night of SLAM i did a OCLT and had only lost 2ppm FC with no CC. After the second night of SLAM I did a OCLT and lost 0 FC. This did not seem right since I use so much FC during the day... I did a CYA test and it is now 0. I tested it again and it is indeed 0.

I currently have 2 socks full of CYA pellets floating in front of the skimmers...

This seems really strange to me. From what I have researched and read this seems really rare. I'm going to be testing very closely to see what happens. It may be time to use up these leftover chlorine pucks since I need CYA.
 
I backwash whenever my gauge shows the psi raises to the point my gauge shows. On my gauge it has a 10 psi range knob that I set when I backwash. Once it raises 10 psi since last backwash I do it again. My attn is usually drawn to it when the flow from pool inlets start to seem low.

With that said I do it roughly every 2 months.
 
Hi Chloe,
Backwashing the filter of course takes a bit of water from the pool. Along with the water goes a bit of CYA every time.

Also, I know you folks over in Mississippi also had a 10 Tons of rain this spring like we did here in East Texas. If your pool overflowed or you had to empty water to prevent it from overflowing, then along with that water went the CYA. I'm sure thats what's happened to it.

hope this helps solve the mystery!




Cloey123 said:
I purchased my house at the beginning of the summer last year and my CYA was around 220. I did several partial drains and got it down to 50. Since it was at 50 last summer and i only use liquid bleach as my chlorine I have assumed it was still 50. I have only tested my FC a few times this year and have been adding the same amount of chlorine every night that I did last year and it has been staying crystal clear. This weekend I noticed it was a bit dull so I tested FC and it was 0 so I began a SLAM based on CYA of 50. I got my FC up to 20 and it was going away really fast during the bright hot day (95 - 99 degree in full sun). After the first night of SLAM i did a OCLT and had only lost 2ppm FC with no CC. After the second night of SLAM I did a OCLT and lost 0 FC. This did not seem right since I use so much FC during the day... I did a CYA test and it is now 0. I tested it again and it is indeed 0.

I currently have 2 socks full of CYA pellets floating in front of the skimmers...

This seems really strange to me. From what I have researched and read this seems really rare. I'm going to be testing very closely to see what happens. It may be time to use up these leftover chlorine pucks since I need CYA.
Click to expand...
 

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Divin Dave said:
Hi Chloe,
Backwashing the filter of course takes a bit of water from the pool. Along with the water goes a bit of CYA every time.

Also, I know you folks over in Mississippi also had a 10 Tons of rain this spring like we did here in East Texas. If your pool overflowed or you had to empty water to prevent it from overflowing, then along with that water went the CYA. I'm sure thats what's happened to it.

hope this helps solve the mystery!
Click to expand...

We did get a lot of rain earlier in the year. I never got enough rain to overflow but I did have to drain an inch or two off about 3 times... but with this in mind I would have to replace 50% of the pool to reduce it from 50 to 25. I do not see how it is possible for this to have caused my cya to go from 50 to 0 (assuming 0 - it is clear and black dot is highly visible when tube is full).
 
If I'm not mistaken, you can lose 2 ppm of CYA per month due to oxidation and other reasons. I saw this in a post by chemgeek...so let's say you lost 2 ppm x 12 = 24 ppm, add to this the dilutional effects caused by rain, it seems entirely possible to have zero CYA over the course of 1 year.
 
jaduck said:
If I'm not mistaken, you can lose 2 ppm of CYA per month due to oxidation and other reasons. I saw this in a post by chemgeek...so let's say you lost 2 ppm x 12 = 24 ppm, add to this the dilutional effects caused by rain, it seems entirely possible to have zero CYA over the course of 1 year.
Click to expand...

Ahh, that I had never read. This could indeed explain it. Needless to say I will be checking it more often.
 
That 2-3 ppm CYA per month loss is with a covered pool and is from chlorine oxidation of CYA. It may be higher in a pool exposed to a lot of sunlight (from some oxidation of CYA by hydroxyl radicals formed from breakdown of chlorine from sunlight). So while it is still true that CYA degradation is too slow to be able to use only Trichlor pucks as an exclusive source of chlorine, it is nevertheless a factor to consider in maintaining a CYA level over many months. Testing CYA twice a season for a summer season makes sense -- once upon opening and again mid-season (optionally again at end of season). In a hot spa, the CYA loss is around 5 ppm per month which is why in the Dichlor-then-bleach method one uses Dichlor about once a month to maintain the CYA level.
 
I test my CYA a couple days after I backwash. After 2 or so back-washes, I can see a reduction. I also have a large sand filter that uses quite a bit of water at each backwash. My pool also receives at lot of full sun. I look at it as a blessing. No problem using the pucks when traveling. :cool:
 
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