My Dad is converting his pool and we have an issue that I can't comprehend... His pool is 18x33x48 and he has been using the ool calculator to determine his amout of bleach to add... He is using the TF100 test kit, and from what I gather, he is testing correctly for FC's... Here's the confusing part... When he tested tonight, he got 13 for his FC's... He put the amount that the calculator said and tested 1 hr later.. His FC level ROSE to 17... I had him retest with me on the phone and it had dropped to 16.5...Now... If he has all his levels right (Gallons and bottle size) WHY would the FC's RISE??? I am TOTALLY Blown away by this... Any ideas?? Today marks 1 week on the conversion and his water SPARKLES!!! He's using a Hayward Sand filter and as stated above 18x33x4ft... His actual water depth is 3'10.5"... He has been using OVAL on the calculator but I think it should be RECTANGLUAR, but when checking, it really doesn't change all THAT much... Again, Any ideas?????

HELP!!!

If he added bleach, you'd expect the FC to rise. It's the measure of unbound chlorine in the water, and bleach adds chlorine.

I agree... I WOULD expect it to rise... My point is, and I may not have said it right, but he put in the pool calculator, for the target to be 15... He added the recommended amount to raise it to 15... However, it went to 17... What gives??? This is not the first time he has tested HIGHER than what it was supposed to go to?? He has ALWAYS put 15 as the targeted amount...

I get 65oz to go from 13 to 15 ppm in his pool. Is that about what he added?

Perhaps the pool is smaller than the gallonage he is calculating

Sounds like the pool water gallonage is lower than calculated???

What is your dad using for "Size____gallons" in the Pool Calculator?

What % bleach/LQ is he using?

Edit: Okay, you type faster

His pool is 18x33x4 and he is using 182 oz bottles of REAL clorox which is at 6%... I have verified all that... It has me utterly flustered at this point..... When he went from 13 to 15, he said it told him 2 quarts and change (74 ozs figured at 17800 gallons)... and thats what he told me he added...

That's what I was thinking too... I had him pull a tape on it and it was 18x32 and his actual water depth was at 3'10" to 4'....

It is acting like one of the following is happening:

1. He is adding too much just because...

2. the pool calc has a glitch (which I doubt because Mine works WONDERFUL!!)

3. Something is askew in the gallons/bleach configuration...

I am DUMBFOUNDED!!!

Maybe a lot of variables going on:

1. Pool volume inaccurate,

2. Testing error, or

3. Maybe Dad just added a little extra bleach.

It may have you scratching your head, but it will all get worked out in the long run and his pool will succeed with the conversion.

When I do the calculation I get that he actually has 16,500 gallons. So there may be some of the difference. I also know that I tend to be a bit generous when adding LC so he may be doing the same.

Mike,
One of my readings during my conversion..I added to bump to 15 and when I read it an hour later it was 16. I just didn't add any bleach after that reading and went on with it.

Deb

you are talking about cl rising 3 ppm instead of 2ppm, which i find
is insignifant.

Adding one gallon (128 ounces) of 10% chlorinating liquid should add 4.3 ppm of FC to my 24,000 gallon pool. It is not unusual for my DPD-FAS test (done 1-2 hours after adding the chlorine) to read as a 5-6 ppm increase in FC. I've never tested the strength of my chlorinating liquid, but I'm guessing that some of the gallon jugs I'm buying sometimes has a concentration higher than 10%, sometimes by a significant amount.