Abnormally High Chlorine Loss (I think...)

KatyTx

Member
Aug 7, 2009
11
Katy, TX
I started on the BBB method about a year ago, so this will be my first full summer of use with the new method. The recent threads on BBB costs and chlorine usage have me wondering if I am doing things correctly.

The lastest test results are as follows:
FC - 7
CC - 0
pH - 7.6
TA - 70
CH - 270
CYA - 40
Borates - 40
Temp - 88 deg

The water is clear and sparkly, and the overnight chlorine loss last night was zero.

Firstly, FC will drop to zero in 24 hours, and I use one, 182 oz jug of 6% bleach per day. At that rate, I spend $76 + tax per month on chlorine alone. (The pool is in full sun all day, and the pump runs 8 hours.)

Secondly, the PH is ALWAYS high, and I have grey patches on most of the bottom of the pool as seen in this thread. I've been a little lax on the PH maintenance, but I now add about 1.25 gallons of acid per week.

Lastly, I have noticed what appears to be black algae in a few spots on the flagstone perimeter and also in on the floor; some as large as a dime, but "hidden" under a thin cap of plaster. A little chipping and spot brushing will clean it off, but I get tired of holding my breath... :roll:

So, why so much chlorine usage? Is it normal in this heat? Why does my PH run high? If I don't stay on top of it, I'll see 8.2 in a heartbeat. The algae has been there a few weeks...not increasing or decreasing. What is the next step to clear it up?

Todd
 

ShockerLU3

Well-known member
Jun 27, 2010
80
Toms River, NJ
I can't speak to all the questions but I had a similar problem with chlorine demand and a similar setup. Full sun all day, high 90 deg. temps, Cya of 40, and 10k gal. Ultimately, I raised the Cya up to 50ppm and that seems to have lessoned my "burn off." I figure that I rarely need to shock and if I get into trouble where I need to shock for extended periods I can always do a drain and refill first.
 

woodyp

Mod Squad
TFP Expert
LifeTime Supporter
Apr 17, 2010
10,576
East Texas
That algae keeps on eating up your chlorine and will until you properly shock it, that is reaching and MAINTAINING the shock level for your cya level until you have no more than 1 ppm overnite loss. See pool school for more shocking info.
 

JasonLion

TFP Expert
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May 7, 2007
37,880
Silver Spring, MD
The most likely possibility is that your CYA level is actually a little lower than you think it is, which would have exactly the effect you describe.
 

KatyTx

Member
Aug 7, 2009
11
Katy, TX
Thanks Jason. How much higher should I target? I have some Ram stabilizer from the previous owner. It is at least two years old. Does it go bad?
 

JasonLion

TFP Expert
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May 7, 2007
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Silver Spring, MD
Stabilizer will last more or less forever as long as it stays dry and doesn't get extremely hot.

I would try adding 20 ppm worth and see what that does.
 

anonapersona

TFP Expert
LifeTime Supporter
Nov 5, 2008
2,598
JasonLion said:
Stabilizer will last more or less forever as long as it stays dry and doesn't get extremely hot.
Hey, Jason, how hot is "extremely hot"?

Katy is not all that far from me, and my temp sensor that is at the pool equipment says air temp is 104 right now, 4:40 PM, and pool temp is 92. Could'a been higher at 2 PM I'll guess. Other side of the house in the shade is reading 88 degrees currently. So on days when the air temp is more like 98 or so, that pool equipment in the sun could be reading even hotter.

So, is that "extremely hot"?
 

JasonLion

TFP Expert
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May 7, 2007
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Silver Spring, MD
Cyanuric acid is stable well over 200 degrees. Bleach is very much affected by temperatures like 100 degrees, and some other forms of chlorine have problems starting at perhaps 180 degrees or so, but pretty much everything else is fine until significantly higher temperatures.
 

anonapersona

TFP Expert
LifeTime Supporter
Nov 5, 2008
2,598
JasonLion said:
Cyanuric acid is stable well over 200 degrees. Bleach is very much affected by temperatures like 100 degrees, and some other forms of chlorine have problems starting at perhaps 180 degrees or so, but pretty much everything else is fine until significantly higher temperatures.
Gosh, I just love this place... where else can you get this sort of info just for asking? Thanks.