Help with extremely high cya

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C

chrismichaelson

0
Aug 9, 2015
27
Waxhaw, NC
Pool Size
18500
Surface
Plaster
Chlorine
Liquid Chlorine
I finally got tired of relying on the guys at the pool store advising me on how to treat my pool. I've been fighting to keep FC levels up for two years and they never told me my cya levels were off the charts and a cause of my problems. They just kept selling me stabilized chlorine. I've been adding more and more chlorine (now using cal chlor) to keep the levels at barely readable levels. So far, the pool looks great, but at a heck of a cost. This summer I found this site and I'm learning. A lot. I got my TF 100 test kit a couple of weeks ago and am learning how to use it.

When I test for cya, I only know that my levels are way over 100, but is there a way to know the exact number? The liquid in the test tube is about half way between the bottom and the 100. I'm planning to drain water off the pool to get the cya level down. Any suggestions on how much I should drain? Also, what are my next steps after I drain and refill?

Thank you all for the help you provide.
 
:wave: Welcome to TFP!!!

There is a diluted test method described in the Extended Test Instructions to give you a little better feel for how high the CYA is.

Regardless, you need to replace water. Depending on you ground water level, you should not drain more than about half the pool at a time.

After you fill, circulate for an hour and retest everything ... post up and we can help with the next step.
 
Thanks, I didn't know about the extended test instructions. I'll try that tomorrow.

My pool is irregular in shape, 8' in the deep end, 3' in the shallow. The deep, shallow, and slope are about equal in area. If I leave about a foot in the shallow end, will that be about 50%? BTW, I don't think the ground water level will be a problem (though I wouldn't drain more than half, anyway). Thanks, again!
 
I conducted the 'extended' cya test and the reading was just below the 100 mark on the tube, so it looks like my cya is above 200, maybe above 225. Ugh. Tomorrow I'll drain 50% of the water and refill. According to the calculator, that won't be nearly enough. I'll post again after the first refill. When I post again, should I continue on this thread?
 
So far... I drained what I thought was about 50% but now I think was closer to 40. CYA was still off the chart. Drained about 30%, still well above 100. Took out another 30% yesterday and FINALLY was able to get a reading of about 90. Drained another 35% today and I am refilling it tonight. I hope to test in the morning to find a reasonable level. FYI, the reason we drained in relatively small increments is that we were paranoid to drain too much for fear of damaging the pool ( first timers fears).
Unsurprisingly, it looks like we have algae growing, maybe pink.
I have about 50# of cal hypo. Once my cya is down, can I use this to shock (until I use it up) before switching to liquid?
Thank you all for your help. I really appreciate how you share your knowledge.
 

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Looks like you need to get that FC up ASAP to at least the target of 7 based on your CYA of 60. With a CC reading of 1.5, something is getting eaten-up and in the transition phase of oxidation, so keep that FC healthy to avoid a SLAM. You might squeak though it. :)
 
Thanks to all. I'm going to raise the FC but, due to work, probably can't start the SLAM until Wednesday. I'll stock up on bleach. I've never used bleach for chlorination. Any guesstimate as to how much I'll need for the SLAM?
 
chrismichaelson said:
Thanks to all. I'm going to raise the FC but, due to work, probably can't start the SLAM until Wednesday. I'll stock up on bleach. I've never used bleach for chlorination. Any guesstimate as to how much I'll need for the SLAM?
Click to expand...
Use Pool Math. Check for your SLAM level and it will tell you how much of a certain % of bleach/liquid chlorinator you need to add to your size/gallons of pool
 
Good job getting that CYA number under control. At the bottom of Poolmath there is a tool called effects of adding chemicals. Enter your gallons at the top and select the chemical and weight and it will tell what the result will be in your pool. The 50# of cal hypo will add 100 to 150 ppm of CH to your pool depending on the percentage.
 
As usual, thanks for the quick and informative responses. I've played with the Poolmath calculator, so I can see how much bleach I'll need to start the SLAM. I don't know how much bleach I might need to maintain the shock level for the necessary time (I know this would only be a best guess).
I hadn't noticed the effects of chemicals tool at the bottom of the Poolmath page. Thanks for pointing that out, pooldv.
 
I brought my FC up to 24 on Monday, but for Monday and Tuesday could only add bleach twice a day. Beginning Wednesday, I started the full SLAM process, checking the FC and adding bleach hourly, as much as possible, keeping the FC at 24. Have been maintaining that routine since then. Yesterday I also backwashed the filter and in the process drained and replaced about 1000 gallons of water. On Thursday morning, the OCLT was 4.5 (CC was 1.5), this morning it was 3.0 (CC was 1.0), so I guess we're making progress. The water has never looked better. When I tested yesterday, my other levels were:
CYA: 60
CH: 325
TA: 70
Unfortunately, we seem to have a residual problem from our high CYA times: We always seemed to have some growth inside the skimmer, just above the waterline. I scrubbed the skimmers clean when I was draining water last week, but noticed the growth had returned yesterday, growing just above the waterline. I'm attaching pictures in the hopes someone can ID the problem (PLEASE don't say black algae!). I don't see anything in the pool and don't notice anything coming up when I brush.
Is there anything else I should be doing?
Thanks!

IMG_0633_small.jpgIMG_0635_small.jpg
 

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