New Test Results - CYA increasing, and FC dropping

tim_pool_newbie

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Oct 6, 2009
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Having been on the BBB method and using a TF100 test kit for about a week now, I'm puzzled by the seemingly voracious appetite for bleach that my pool has. It seems that I'm adding about a gallon a day (give or take) and yet I still don't manage to get the level up to my target for my CYA level.

I'm also not sure I "get it" with my CYA testing yet!! Last week I was getting a CYA level of 50, and now today it's more like 60. Should the black dot in the tube be just going away - or completely gone from sight? If it has increased by 10ppm in a week, I don't know how since I'm only adding bleach, an algaecide (2x month) and Les-iron (1x week for first 6 weeks).

Here are my test results from today:

FC - 4.5 (after adding 2 gallons of bleach last night)
CC - 0
TC - 4.5
pH - 7.6
TA - 70 (FINALLY getting better results with this test!!)
CH - 210
CYA - 60
Temp - 77

Am I doing OK, and should I just keep adding bleach?

P.S. This is a brand new plaster pool (about a month old), and I never really saw the pH spike that they told me I would see. Still have lots of bottles of pH Down on the shelf!!
 

frustratedpoolmom

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May 20, 2007
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SWSuburban Chicago, IL
What brand is the bleach and how big is the bottle (in ounces?)
Algaecide is unneccessary and can also consume some of the chlorine, is there a particular reason you are using it?
 

duraleigh

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Apr 1, 2007
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Sebring, Florida
Hi, Tim,

About the best you can do with the CYA test is plus or minus 10ppm anyway, so you could consider that the same result. You aren't doing anything wrong with your testing and it's not really increasing.

A gallon of bleach each day for your size pool might be just a little excessive. Have you done an overnight FC loss test to check for something organic (like algae) in your pool?

The algaecide will consume some of that bleach and it is really unnecesarry......are you using it for a specific reason?
 

tim_pool_newbie

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Oct 6, 2009
164
I'm using the generic bleach purchased from WalMart in the 182oz jugs. But I'm measuring out just as much as I need based on Pool Calculator. I add the bleach around 4pm(ish) and the next morning my chlorine readings are low again.

As for the algaecide, the startup company gave me this chemical (along with Les-Iron) to add to the pool. I am supposed to add 1/2 quart of algaecide every 2 weeks during June, July and August. When I questioned the use of the Les-Iron in an earlier post, someone made the comment that I should continue to use these if the PB said to - so as not to void any warranty. Makes sense, so I've continued to use both products at least until I've gone through what they gave me to use.

Water is crystal clear (has always been since original fill), so I don't really suspect algae. Maybe I'm just not getting enough in there the first time to keep it at the level needed based on my CYA level (???).
 

geekgranny

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Aug 20, 2009
1,358
North Central Texas
duraleigh said:
Hi, Tim,

About the best you can do with the CYA test is plus or minus 10ppm anyway, so you could consider that the same result. You aren't doing anything wrong with your testing and it's not really increasing.
I just noticed, the other day, doing a CYA test on a somewhat bright but overcast day, that the reading varies according to where I hold the tube. So I've started holding the tube at the very top to keep it consistent (as much as is possible). I was doing the test over and over using the same solution and it did vary most when I switched between holding it lower on the tube and then suspending it down, holding it at the very top so that all the ambient light reached the solution.

gg=alice
 

chem geek

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Mar 28, 2007
12,082
San Rafael, CA USA
It sounds like you are losing a lot more than 1 ppm FC overnight in which case something is consuming your chlorine. I suspect it might be the Les-Iron metal sequestrant. I know that some metal sequestrants significantly increase the chlorine demand -- I used such a product in my own pool and will never use it again. After the initial treatment, I was using 5 ppm FC per day which then dropped over the next days but took over a week to get back to "normal" and that's without adding any more doses. The better metal sequestrants use HEDP that is far more resistant to breakdown by chlorine. Unless you have a known metals problem in your pool, you shouldn't need to be using a metal sequestrant.
 

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