Intex gallon size discrepancy; today's water readings

[SadieMcGee13]

I was reading a thread from 2009 and didn't realize it so I posted a new thread to hopefully get some help today.

I have the Intex AG 18' round x 48". The literature that came with the pool said 6400 gallons and the pool store said 7600 or so. I was thinking it was because I have the Ultra Frame and where the sides meet the bottom are not exactly square, but rounded. But now I wonder if I've been underchlorinating because I'm not using the correct amount of gallons in my calculations... Last night I added bleach using the Pool Math calculator to bring up my FC from 2 to 5. I added the amount per the calculator, but this morning my FC was only 2.6. My SWG was on yesterday too. Here are my measurements as of this morning:
FC 2.6
CC 0.6
pH 7.6
TA 52
CH 170
CYA 60

My CYA has fallen from 70 to 60 in a few days. So, it seems I may need a teensy weensy bit more...? Any help is appreciated. Thanks in advance.

 

[Richard320]

It's more likely you have an algae bloom starting and it just isn't showing up as murky water yet. I'd chlorinate heavily today and run an overnight loss test to ensure there's nothing growing in there. You can kill it off fast if you catch it early enough.

 

[SadieMcGee13]

NOOOOOO!!!! I HATE ALGAE.

Ok, any advice on which gallon size I should refer to when measuring bleach to chlorinate heavily today?

 

[duraleigh]

6400 gallons is close enough. 7600 is incorrect.

 

[SadieMcGee13]

Thank you duraleigh!

 

[danpik]

My calculation at 48" depth of water is 7610.381 gallons. At 40" water depth it is 6341.983 gallons

 

[domct203]

6700 gallons works perfect for me using Pool Math. I add 7-8 oz of 12.5% chlorine for every 1ppm I want to raise and that's what I get.

30 minutes after you add chlorine (filter running) test and see if you have hit your target.

If you want peace of mind for the algae do an OCLT (SWG off)

Dom

 

[SadieMcGee13]

Ah, thank you Dom!!! I have added 8.25% bleach TWICE at the recommended amounts per Pool Math and have not been able to get my FC up above 3. I had an inkling that I was using too few gallons in my calculations. This morning my readings are: FC 2.8, CC 0.4, pH 7.6, CYA 75. I've been trying to get up to 5ppm of FC and have not yet. I'll readjust and try again. Thanks again.

 

[Beens]

Are you sure your bleach is fresh?

 

[MarianParoo]

Also, unless you need the accuracy for a tough OCLT, for FC/CC testing use the 10ml measure in your testing vial and multiply your drops by 0.5 instead of 0.2. Use the same powder and reagents.

Check freshness of bleach and liquid chlorine (pool shock) by looking at the date code. 15212 is the 212th day of 2015.

 

[SadieMcGee13]

I thought so. I bought it the day before I used it. I'll check the code as suggested by MarianParoo.

- - - Updated - - -

Thank you. I'll check the code! I just bought a 3 pack of Clorox from Sam's Club, but it could've sat in a warehouse somewhere, huh?

 

[MarianParoo]

Yea, you can never know where they stored it before they brought it inside. When I am buying boxed chlorine, I open the box and pull out a jug so I can read the date code. I have done this to multiple boxes at times. I just bought a 4-pack of 12.5% from Menard's for 3.99/gallon. 2 days old. The first box I opened was 5+ weeks old. Glad I checked another box!