FC won’t go up

Devinpool

New member
Jun 19, 2019
3
SE Ohio
Hello all, let me preface this by saying I’m using test strips right now and some data from my local pool store. I know I’ll need to get a proper kit soon.

I haven’t been able to get my FC levels up, they were showing 0.3 ppm when I tested at the pool store and I had combined chlorine of about 3.4 ppm. I figured I should try and SLAM the pool to break the combined chlorine.

I added 3 lbs of 53% shock and a gallon of 10% bleach. From the pool calculator app this should have brought my levels up to about 12 ppm. I tested the water with a strip about 7 hours later in the day and was showing 0 ppm still. The CYA should be close to ok, I added 4 lbs of stabilizer the previous day after having only 5 ppm. And the pH and alk are close to ideal.

The pool is looking good, I can see the bottom with little cloudiness 9ft deep in the deep end. Is the test strip garbage and I probably am at SLAM levels or is there something else that could be eating all the chlorine so fast?

Thanks in advance!
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
:wave: Welcome to TFP!!!

Sorry, can trust the test strip results could mean the FC is high or low.
If you could accurately test the FC and CC independently we could start troubleshooting.

What was your CYA level before you added the 4 pounds? Was this a new fill or just opening?
 

Devinpool

New member
Jun 19, 2019
3
SE Ohio
We opened a week or so ago and had gotten it looking pretty good after being really green. The CYA was 5 ppm before the addition of more stabilizer.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
14,420
Evans, Georgia
Hiya.

First off- you can't do a SLAM process with "Guess strips"....... there is barely enough accuracy in those things to trust a kiddie pool with them, not to mention a 25k gallon pool!

Not sure what you mean by "break the combined chlorine" but if you mean oxidize the contaminants (the Combined Chloramines) plain liquid chlorine in the proper amounts will do it.

You do not want to be adding other chemicals to a pool if you don't have accurate readings now.... you might overdose that CYA and then be fighting to add enough chlorine to do its job.
The more CYA in the water = the higher the FC has to be to clear a pool up.

Stop using all solid and granular chemicals at this time. You're just adding by products you may not need (such as yet more CYA or calcium). Stick with liquid chlorine.

Maddie :flower:
 
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jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
I am just hoping that your CYA was not converted to ammonia which is why your FC seems to disappear. Because if that is the issue, the CYA you added might be further feeding the bacteria and making more ammonia.

Either way, the answer is more liquid chlorine.
 
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Devinpool

New member
Jun 19, 2019
3
SE Ohio
Dang, wasn’t aware CYA could be converted to ammonia. I guess I’ll have to wait to get more accurate readings to determine if that’s the case. Thanks!
 

jmikeb

Gold Supporter
Aug 4, 2017
298
stillwater oklahoma
imho, i would add 5ppm of liquid chlorine each day (that’s 1.5 gal of 10% ) until your test kit comes.
i would also get the speedstir, it makes testing quicker and more accurate.
oh, and forget the pool store and their magic potions

mike
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Dang, wasn’t aware CYA could be converted to ammonia. I guess I’ll have to wait to get more accurate readings to determine if that’s the case. Thanks!
It is fairly rare, but we see it on the forum more often that I think we expected to.

Possible signs are:
1. Unexplained loss of CYA
2. Very rapid FC losses (like 15 minutes)
3. High CC levels after adding chlorine
4. Low pH (that is not currently caused by the use of acidic Dichlor or Trichlor)