Need to Shock

koliver13

Well-known member
May 17, 2010
115
FC 6
CC .5
PH 7.5
TA 110
CH 250
CYA 70-80

Pool is in full sun 9-8. I add bleach every night usually FC is between 5.5- 7 so i use calculator to figure up to around 9. It takes any where from gallon up. My cc is always .5 I have some gray stuff in the skimmer don't know if it's from bathers, lotion etc. or algae. Wondering if I need to shock is that a lot of bleach to add every night or is it because of sun and high CYA? Thanks for any help.. Maybe I should do a overnight FC lost test. What do you all think?
 

Bama Rambler

Mod Squad
TFP Expert
LifeTime Supporter
Jun 22, 2009
23,047
SouthWest Alabama
I'd recommend doing the overnight test then shock if you need to.

Get a couple of scum balls too. They'll catch most of the stuff you're talking about. It's probably from the swimmers.
 

svenpup

LifeTime Supporter
Nov 18, 2009
835
Sacramento, CA
The question of what is "normal" FC loss has come up a lot lately. 3ppm per day is not excessive. You could do an overnight FC loss test to get a better idea of where the FC demand is coming from and whether you need to shock.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,082
San Rafael, CA USA
If the CYA were truly 70-80 ppm, then the typical chlorine loss starting from 9 ppm FC would be roughly 2 ppm FC while you are seeing a drop of 2 to 3.5 ppm. Though this is still plausible, it does seem a little on the high side (unless you have very high bather load, especially if people are peeing in the pool). The gray stuff in your skimmer may be a sign of excessive organic load in your pool. I presume you have backwashed your sand filter recently and seen dirty outflows turn to clear. You might want to inspect the filter just in case there is clumping with channeling -- that can happen from biofilms though they normally don't form unless the chlorine was too low at some point in time.

As others have noted, a test of the overnight drop in FC would help you determine whether you should shock and/or look for organic contaminants in your pool (i.e. checking the filter, skimmer, pump basket, etc.).
 

koliver13

Well-known member
May 17, 2010
115
Thanks for the input i've been running my robot and not backwashing since the pressure never changes. I guess I need to backwash and do an overnight loss thanks. Oh what is a scum ball?
 

JasonLion

TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
37,880
Silver Spring, MD
A scum ball is a ball made out of a special foam material. You put it in your skimmer and it soaks up any oils, suntan lotion, tanning oil, etc that get into the skimmer. They can be handy if you have oil accumulating inside the skimmer.
 

poolgirl22

Platinum Supporter
LifeTime Supporter
Apr 14, 2010
595
Stephens City, VA
Can these be cut in half and still be effective?
I just got some (oooohhh 33% bigger now!) and it is a bit too big for the skimmer...the lid keeps it in one place.
Plus I'm cheap, err, thrifty, and I like to get the most for my money...Seems like there's a lot of space that doesn't get used.
 

koliver13

Well-known member
May 17, 2010
115
FC 8 after adding bleach and checking 45 min. later. But this morning checked it was FC 9. Guess I need to check again tonight and wait longer after adding the bleach. I also need to back wash at least once a week even know I'm using the robot? I guess just the amount of sun my pool receives and the high CYA is the reason I need to add so much Bleach every night. Next year there will be no pucks or sticks used in the pool and hopefully I can keep the CYA down some. But with high sun exposure do you need to keep CYA at the higher end? thanks again for the input. This site is great!!!!!
 

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