CYA removal, and balancing after

[dannyk58]

Hello, and thanks for any input. I am still learning this pool chemistry thing. My CYA is off the charts, what I want to know to avoid this in the future is what causes this? (commercial chlorine tabs?)
Ok, I tried Bio whatever to reduce CYA, worked somewhat, but did not work is the summary.

I will do a water exchange, while the calculator says remove 70%, that is not happening, I was going to do 20-30% for now.

Here is my latest test results, and all my results since acquiring my Taylor K-2006 have been uniform.

FC- .2 (raised daily, using liquid 10% it doesn't last long and requires 32+oz daily)
PH- 7.6
CALCIUM- 600
ALK- 120
CYA- off the charts (black dot disappears with about 1/2" in tube)

My question is, when I do the water exchange what should I do to not mess up the water when adding all the new water?

Next question when filling from the tap, does anyone add some sort of RV type filter to somewhat treat the tap water? Or just adjust after adding?

Thanks so much

 

[chem geek]

For every 10 ppm Free Chlorine (FC) added by Trichlor, it also increases Cyanuric Acid (CYA) by 6 ppm. So yes, your use of Trichlor tabs as your primary source of chlorine is likely the reason your CYA got so high.

Unless you are filling from a well which had iron in it or is high in TA and CH, you usually don't need to filter tap water. If there are chloramines in it from chloramination disinfection, you can take care of that with chlorine. You shouldn't need to do anything to your pool water during this water exchange process other than maintaining the water parameters, especially the chlorine level which will drop some as the water is replaced.

You need to add more chlorine now and get your FC much higher. The fact that it is getting used up quickly with the high CYA level means you have an impending algae bloom even if its not yet visible. 32 fluid ounces of 10% chlorinating liquid in 15,500 gallons is only 1.6 ppm FC so you are using WAY too little chlorine. You should be adding enough to get to around 10 ppm given your high CYA level. While this isn't a SLAM to kill off the algae, it should buy you time until exchange some of the water.

 

[Swampwoman]

Danny, I just want to note that at your CYA level there is never an occasion where you should be letting your FC drop to .2! That's an invitation for algae, not to mention a complete lack of sanitation.

Please review the chlorine:cya link in my signature and dose to a level that keeps your MIN for your CYA available until you dose again.

This notion of the relationship between maintaining the FC according to the chart and your CYA level is the single most important takeaway for a trouble free pool

 

[Defgufman]

32 ounces isn't enough chlorine with really high cya.
can you do a dilution test so we can get you a number to stay at? For now put 2 gallons of 8.26% bleach in there so we don't explode with algae.