CYA off the charts....

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BadOleRoss

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Apr 30, 2011
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Lynchburg VA
Just go my shiny new test kit in and decided to check out the water. FC was 0, CC was 0, :cry: PH was 7.4.....decided to go ahead and check the CYA with the FC/CC being zero and it was well over 100. So, I doubled the sample and kept the solution the same(not sure if this was right but it seemed logical) and I was still only able to put 1/4" of water in the tube before the black dot was gone. I added 2.6G of bleach to the pool to see what kind of reaction I would get from FC/CC and it (FC) went from 0 to 1.5%, that was after 4 hours of the pumps running. The pool is 27000G, I really don't want to have to change 75% of the water! I was looking at my most recent report from my local pool place and they recommend your CYA being between 30-300....why so high?
 
Welcome to TFP!

No need to dilute and retest and all of that stuff. Your first test for CYA gave you a value of > 100 ppm. There is your answer and that is all you need to know.

I understand that you may not want to change out water. Unless you do though, you will continue to have problems associated with high CYA such as the requirement to maintain an incredibly high level of FC in there at all times. Secondly, there is no real accurate way to know exactly what your true CYA level is once it is over 100 ppm. The bottom line is that you need to change out water. It's that simple.

What type of pool do you have? It would be helpful for you to put your pool specs into a signature line so that we can all see exactly what system you are running.
 
BadOleRoss said:
OK, doing it the right way still shows a CYA of 100, but that would be 200 because 1/2 of my water was tap water. According to the pool calculator I need to change out 80% of my water!
Click to expand...

Possibly, but keep in mind that once you start diluting samples with this and that, accuracy suffers considerably. I would change out water in small increments, say 20% at a time, and retest along the way. You have a vinyl liner pool and if you drain too much water out of it all at once, you risk creating problems with your liner becoming unseated. Vinyl liners depend on the pressure exerted on it by the pool water to remian in place.
 
I am going to give my pool installer a call tomorrow and see what his thoughts are draining and refilling. I am pretty sure I can drain down to the bottom of the shallow end with little or no affect on the liner...not sure about going much further. The pool place tested my water a few weeks ago and gave me a CYA number of 100 so I just might start with that as a jumping off point. Several weeks ago my pool place said I had a high C demand and had me dump 75lbs of shock in the pool to meet the demand so my pool would show FC again. Was this all due to the CYA and the pool people being clueless?
 
75 lbs of shock is very very extreme. If it was dichlor it will have raised FC by 184, raised CYA by 168, and lowered PH by 7.0!!!! If it was 65% cal-hypo, it will have raised FC by 215 and CH by 151.

When draining a vinyl liner pool you should always leave about one foot of water in the shallow end. If you don't the liner can shift and will need to be reset, and if it is old enough it may tear while being refilled.
 
Talked to my pool installer, not the guys that gave (sold) me 75# of shock for my pool and he said I was OK to lower the pool to within 6" of the bottom of the shallow end. Much lower and he said the same thing you said...I risk the liner pulling away from the walls. So, I have lowered the pool water, the liner remained in place, and am now in the refill stage. Once filled I will retest my CYA and see how it looks.
 

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This was actually the 2nd time this smae poll store had me to this. I got the same story at the tail end of last year when I dumped about the same about the shock in the pool to take care of this high demand issue. This was before I found TFP and didn't know anything about what was really going on in my pool. Oh well, live and learn I guess!
 
The CYA is caused by your chlortabs with stabilizer. Stabilizer = CYA. The way to keep it from rising is don't use the tabs when your CYA is where you want it to be.

Unfortunately a partial drain and refill is your best option.

You might try mixing your pool water with 1/2 tap water and see what the results are, although it'll affect accuracy somewhat.
 
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