CYA loss

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simonoaks said:
Really?

Does the FC not kill it ?

I actually have a bacteria test kit, as the reason I took over my own pool was because my 4 year old has been doing major surgeries on her leg and swimming in pool is really good for her - but there are open wounds down to the bone.

I will test for bacteria too.

thx
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Yes, proper chlorine level will kill the bacteria, and all bacteria, in the pool. The times when bacteria consume CYA occur with a perfect storm of water temp and low/no chlorine. Maintaining your chlorine level above the minimum level at all times for your CYA and the Chlorine CYA Chart will keep your pool sanitary and safe.

- - - Updated - - -

simonoaks said:
Also,

I have just been reading back at some old posts from when I first started out on here. My CH was at 525 in June last year - now 260, so that shows dilution, which could account for the CYA loss too, right ?

Also, should I increase CH, and what to ?
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Yes, exactly right. If your pool is being overflowed by rain and diluting your CH it will also dilute your CYA and salt. CYA will also be consumed 3-5ppm per month by chlorine.
 
Cool. So 5ppm CYA loss by FC, plus the rain dilution, probably works out about 70ppm CYA loss that I have seen in 6 months.

Just added another Gallon of CYA, which will take it to 70ppm. Will add 8lb of CH too, to bring that up to 350.

I should not have taken my eye off the ball during winter by only managing FC, PH and pool scrub/ filter clean every week.
 
Just caught up on this thread. Seems like a huge CYA loss over a short period of time. You don't have an autofill device of any kind? Sounds like you have an autodrain or overfill device but nothing that automatically would fill the pool if the water level dropped?
 
I have found I lose most of my CYA over the winter. I do not bother with it during the cold time. As soon as the overnight temps start hitting and staying in the 50s I add new CYA. I have found this works well for me.

Kim
 
jaykull said:
Is this true? I thought the only way to lower cya was replacing the water or ro?

Sent from my SM-N910P using Tapatalk
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Yes. Chlorine oxidizes CYA very slowly. 5ppm per month is a high estimate though at pool water temps. The effect is more pronounced in hot tubs and spas that run closer to 104F. In those, the degradation of CYA from chlorine oxidation is easily measurable over time.


Sent from my iPhone using Tapatalk,16k gal SWG pool (All Pentair), QuadDE100 Filter, Taylor K-2006
 

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JVTrain said:
Just caught up on this thread. Seems like a huge CYA loss over a short period of time. You don't have an autofill device of any kind? Sounds like you have an autodrain or overfill device but nothing that automatically would fill the pool if the water level dropped?
Click to expand...

Correct. No auto fill.

So, if that loss is too high to be FC and rain degregation, and I have maintained FC to keep away bacteria, what could it be ?

Thx
 
COuld be that CYA was 50/60 not 70, as it is such an inaccurate test anyway.

Levels look good now:

FC 9.5 (have now turned SWG down from 70 to 38%)
TA - 120
CYA 70-80 (who can really read it perfectly ? lol )
CH - 350

last side question - am I ok with TA at 120 ? Went a bit crazy on the baking soda .

thx
 
There are a few sources of documented CYA loss. Not all of them are very well studied or quantified at this point.

This summary by chem geek is very good, even if it does delve a bit in the deep end of pool chemistry: Degradation of Cyanuric Acid (CYA))

It boils down to a few sources of possible degradation such as bacterial (which would not be possible in a pool that is always properly sanitized), elevated FC/CYA ratio combined with warm pool temps and chlorine breakdown products in sunlight.

EDIT:

At a TA of 120, you'll likely see faster pH rise than you would like. Just keep adjusting your pH as needed with MA and your TA will settle in to a level that results in less pH rise.
 
Thanks, I read all that stuff - interesting.

I think mine was just normal loss due to year round sun, and high levels of Florida rain. Also a factor, is that as the CYA test is so subjective, I could have started at 50/60 not 70. SO maybe I only lost 50/55 in 7 months. In that time, we have had 368 inches of rain, so likely that
 
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