TFP vs pool shop recommendations on FC/pH

Bqtk

Member
Jun 16, 2019
23
Belleville, ontario
Based on a CYA of 60, TFP recommends a FC of 7-9, but my pool shop says 1-3. Am I missing something obvious?
There's also a discrepancy on pH but that's much less of a difference...7.4-7.6 vs 7.7-7.8.
I'm just curious why this might be, and what I should do, especially with FC.
 

homegameroom

Bronze Supporter
Sep 23, 2015
272
Sunrise,FL
PS The folks here only want you to have a trouble free pool; the folks at the pool store want you to come back again and again and again and again.... we don't charge you a dime! (y) And there is a GREAT new video explaining it as well in the Pool School link!
 

aeh0603

Well-known member
Apr 6, 2016
353
San Diego, CA
Pool store advice does not acknowledge the relationship between CYA and FC. Their FC level is appropriate for a CYA of 0. The problem is at CYA of 0, the FC won't stick around very long in the sun, and at CYA of 60, FC of 1-3 is not adequate to keep your water sanitized.
 

Richard320

TFP Expert
LifeTime Supporter
Jan 6, 2010
23,932
San Dimas, CA (LA County)
Based on a CYA of 60, TFP recommends a FC of 7-9, but my pool shop says 1-3. Am I missing something obvious?
There's also a discrepancy on pH but that's much less of a difference...7.4-7.6 vs 7.7-7.8.
I'm just curious why this might be, and what I should do, especially with FC.
The pool store just repeats the standards from decades ago, which completely ignore the effects of CYA. In the US, commercial pools are limited as to how much CYA they can use, and the low FC levels the pool store pushes match that.

If you're scientifically minded, check out Pool Water Chemistry


For the pH: Where do we advocate 7.7-7.8? I've only seen 7.2-7.8.
 

Leebo

Admin
TFP Expert
LifeTime Supporter
Jul 21, 2011
10,079
Eastern Ohio
That's new as of May, I guess. News to me!
In May we updated the wording how to add CYA in the article after discussion between Guides and Experts. The update to an “ideal pH” was made some time ago before the migration to XenForo but after the book was published. I can’t remember the exact date. That said, why do we suggest higher pH than stores? When not using pucks or granular chlorine pH tends to want to increase over time. The rate it increases slows the higher you get. A pH of 7.4 will increase to 7.6 faster than from 7.6 to 7.8. Its best in many instances to keep it towards the high end (and keep a low TA) to slow the pH increase down thus using less acid.
 

beeaton

Member
Jun 11, 2015
11
Houston
In May we updated the wording how to add CYA in the article after discussion between Guides and Experts. The update to an “ideal pH” was made some time ago before the migration to XenForo but after the book was published. I can’t remember the exact date. That said, why do we suggest higher pH than stores? When not using pucks or granular chlorine pH tends to want to increase over time. The rate it increases slows the higher you get. A pH of 7.4 will increase to 7.6 faster than from 7.6 to 7.8. Its best in many instances to keep it towards the high end (and keep a low TA) to slow the pH increase down thus using less acid.
When you say "keep a low TA", what should that value be? I have been keeping my TA around 80, but I am having to add acid every 2 days to bring it back down to around 7.6.
 

Leebo

Admin
TFP Expert
LifeTime Supporter
Jul 21, 2011
10,079
Eastern Ohio
Another spot TFP differs is how we suggest a lower TA level than many in the industry. See what happens if you’re able to lower the TA to 50-60ppm. I’d suspect you’ll see a decrease in acid use and how frequent you have to add it.
 

beeaton

Member
Jun 11, 2015
11
Houston
Another spot TFP differs is how we suggest a lower TA level than many in the industry. See what happens if you’re able to lower the TA to 50-60ppm. I’d suspect you’ll see a decrease in acid use and how frequent you have to add it.
Thanks for the info. I will give it a shot and report back my findings!!