CYA Whacked....

aasbury

Well-known member
Jun 1, 2012
111
#1
So I use the BBB method, CYA got jacked up due to using leftover Di-chlor powder before the switch this year. I literally opened up the pool this year to a black swamp that smelled like a sewer. I mean I really chucked that stuff in there to clear the water. The CYA was around 20 when I started adding Di-chlor powder. After prob 20 pounds of "shock" powder and 20 pounds of "regular strength" chlorine granules I was at 100. i always knew that CYA was a problem, but had thought that the upper limits was 200ppm (pool store). i am at somewhere between 90 and 100 now. When I dilute the sample 50/50 I get 90. Without dilution I get around 100. My water seems OK, though. FC stays around 7. I bump it up a little before we swim and add a little more at dark. There is little chlorine loss overnight and throughout the day. The water is very clear...you can see a quarter on the bottom of the pool and the sunlight dances around on the bottom. CC ranges from 0 to .5. I think it may have been close to 1 once the sample turned almost clear on the first drop. Draining water is not really an option and I really do not care to buy and use that much bleach. So does anyone else have experience or suggestions on maintaining a higher CYA pool?
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#2
You can just keep the FC level up to a minimum of 7 ppm and you should do fine. That'll be enough to prevent algae from growing regardless of nutrient conditions and the high CYA level will make your chlorine loss pretty low, probably 1-2 ppm FC per day. The main risk is if you do let the chlorine level get too low and algae starts to grow since the shock level for killing off algae is very high at the high CYA level. If you were horribly worried about this, you could use an algicide weekly such as Polyquat 60 as insurance, but that's extra cost and not really necessary, but I just wanted to throw out options for you.

So you say you don't want to buy and use bleach, so what exactly are you using right now for chlorination? Is the powder Cal-Hypo or is it Dichlor (or even Trichlor granular)? You want to stay away from Dichlor and Trichlor since your CYA is already so high. As for Cal-Hypo, it will increase Calcium Hardness (CH), but if yours is pretty low, then you could get away with using it for a while. For every 10 ppm FC added by Cal-Hypo, it also increases CH by at least 7 ppm.
 

aasbury

Well-known member
Jun 1, 2012
111
#3
I am using bleach...just lots of it to maintain. I don't care to buy the bleach needed, it is just a pain to drain lots of water from my pool because it floods my and my neighbors yards if i pump the water to waste via my filter. And draining with a sump pump requires 100's of feet of drain hose to dispose of the water. I would rather buy lots of bleach now and only have to remove major amounts of water when i pump it down for closure in the fall. I am just going to keep ahead of the CYA this year and not make the same mistake next year. The CYA is coming down as I backwash and vacuum and remove 3 or so inches of water at a time and refill a little at a time. I hope to have the CYA a little more manageable by mid to late July.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#4
Maintaining a pool with CYA around 200+ is nearly impossible without special equipment. The FC level needs to be so high that the standard PH test won't work, which means that maintaining the correct PH is very difficult. You will be much better off replacing some water.
 

aasbury

Well-known member
Jun 1, 2012
111
#5
I am replacing water...just a little at a time. I will vacuum to waste or backwash for a little longer than usual. The amount of water removed and replaced is adding up. My CYA was about 90 when I checked it earlier.
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,879
Silver Spring, MD
#6
aasbury said:
When I dilute the sample 50/50 I get 90. Without dilution I get around 100.
If I am reading that correctly, it means your CYA level was 180+ when those tests were done. The CYA test will read any CYA level over 100 as 100, and it is easy to misread 100 as 90.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
#7
Sorry I misunderstood. I thought your CYA was 90-100. If it's truly closer to 180, then I agree with Jason that your pool will be unmanageable unless you are lucky. You'd have to keep a higher FC of around 13-14 ppm or so unless you use an algicide at extra cost, such as Polyquat 60. If you really don't want to dilute the water faster than you are, then I'd say those are your two options: higher FC level (roughly 7.5% of the CYA level) or use of a supplemental algicide. Or cross your fingers and hope that your pool is sufficiently poor in algae nutrients to not get algae at a lower chlorine level.
 

aa62579

Well-known member
May 24, 2011
409
North Central Texas
#8
JasonLion said:
aasbury said:
When I dilute the sample 50/50 I get 90. Without dilution I get around 100.
If I am reading that correctly, it means your CYA level was 180+ when those tests were done. The CYA test will read any CYA level over 100 as 100, and it is easy to misread 100 as 90.

For clarification, when you did the dilution method, did you come up with 45 that you multiplied by 2 to get 90? Or did you come up with 90, that needs to be multiplied by 2 to become 180.

I interpreted it as your final number was 90 with one method and 100 with another method. +/- 10 is common with this test, so that could be possible.