CYA test question

TCpoolnoob

Well-known member
Apr 27, 2015
56
Richland WA
My pool was green over the winter so I threw in 4 gallons of bleach and fired up the pump a couple weeks ago. Turned out my pump needed replacing so I ordered up a new one, installed it and ran it for a week at approximately 5-9 Chlorine. Mainly, I was just running the pump, back washing the sand filter, cleaning out the skimmer baskets and not really monitoring the chemicals.

During that week or so, the water turned from green to a real pretty milky blue color and doesn't seem to want to clear further.

I'm ready to get the pool going and address this milky water so I did my testing today.

Chlorine is at 5
CC test was clear (surprised)
PH 7.2
But the CYA was reading 90 which would be significantly higher than the 50 reading I think it was at last season.
I'm not using any pucks or shock so I don't know where the extra CYA could have come from.

The water in the pool is very milky making it nearly impossible to see the bottom of the 3ft deep shallow end.

I suspect the milky water (think a glacial river for those of you near mountains) is clouding my CYA test results?

Is this possible?

I'm wanting to slam the pool to see if I can address this cloudy water issue but the CYA reading at 90 calls for a little over 7 gallons to get to slam while a CYA of 50 calls for half as much.

Do I trust my gut and slam it for 50 or take the results for what they are and slam it for 90?

It's not a huge financial hit either way but I pay $5.00 a gallon for 10% here and it does add up. No sense in wasting chlorine and money if I don't have too.
 

Donldson

TFP Expert
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In The Industry
Jun 12, 2009
3,343
NW Ohio
Fill the CYA tube to the top with straight pool water and see if the dot appears cloudy at all. If it is crystal clear then it is not affecting your results.

CC comes from chlorine reacting with ammonia or some such substance, a normal algae bloom will not usually cause significant CC if any.
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
CYA doesn't get into your pool unless you put it there.....somehow. If not pucks, dichlor shock?

The cloudiness in your pool water should have little to no affect on your CYA. To confirm this, take a sample of your plain pool water and put it in the CYA view tube and run the test. Can you see the dot? If your tube is filled and you can see the dot, there is no interference.

If, somehow, you read 20 or 40 with just pool water, subtract that reading from your CYA test and that will reveal your true CYA.
 

TCpoolnoob

Well-known member
Apr 27, 2015
56
Richland WA
Thanks for the advice!

Water looks clear in the tube to me. I know the CYA test is subjective but I don't think my eyes could be off this much from one year to the next.

If the test is correct, I have 2 options.
1. Drain and refill 44% of the pool water. I'm not super happy about this as the current water was only in there for 1 season.
2. Just slam it at current levels and keep the pool around 10 on the chlorine scale all Summer.

I think what I'll probably go ahead and slam it now and deal with the high CYA once it warms up a bit more here.
 

AimeeH

LifeTime Supporter
TFP Guide
Apr 2, 2012
2,002
Columbia SC
That is a big difference to be testing error but..........just to be thourough, remember that lighting conditions are important for the CYA test. You want to be outside on a sunny day with your back to the sun and holding the tester tube at about waists height. :)
 

Ezbagr

Member
Feb 27, 2016
7
Eastern Tennessee
One thing that I ran into last year when I opened my pool and tested my cya it showed high also so I drained half the pool and checked it again and it was around 50 and then I ran out of the r-0013 agent and had to get a new bottle and when I checked it with the new r-0013 it showed like 20-my conclusion was the r-0013 went bad over the winter.
I have a very similar thing this year when opening, I had ordered the 50 cya solution to check and to me it also shows high so I am going to order some new r-0013 and go from there.

Sent from my XT1254 using Tapatalk
 

TCpoolnoob

Well-known member
Apr 27, 2015
56
Richland WA
One thing that I ran into last year when I opened my pool and tested my cya it showed high also so I drained half the pool and checked it again and it was around 50 and then I ran out of the r-0013 agent and had to get a new bottle and when I checked it with the new r-0013 it showed like 20-my conclusion was the r-0013 went bad over the winter.
I have a very similar thing this year when opening, I had ordered the 50 cya solution to check and to me it also shows high so I am going to order some new r-0013 and go from there.

Sent from my XT1254 using Tapatalk
Good point, thanks for bringing it up!
Actually, the reason I didn't post my Calcium results is that it appears one or some of my solutions for that test are no longer working. I dropped in 100 drops and it never turned blue.
I'll order up a new test kit and see if that explains some of the variance in CYA level.
 

duraleigh

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Apr 1, 2007
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my conclusion was the r-0013 went bad over the winter
Certainly remotely possible but not likely. R-0013 is an inert substance and there is virtually nothing in it to go bad. I cannot account for the test discrepancies.
 

pzampino

Member
Jul 7, 2016
21
Raleigh, NC
I would SLAM it according to the 90 reading. The worst thing that can happen is that you waste a few $$. I was too conservative with my early SLAMs last (my first) season, and I tolerated less-than-crystal-clear water for too long because I didn't SLAM it with a high enough chlorine level. Then I performed a proper SLAM, and saw the results, and I've had crystal clear water ever since. I found that I can do it once at the correct level, or do it multiple times with mediocre results.
 
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