UPDATE HELP PLEASE: FC dropping during hot days! Bad cell or normal?

gobblerhuntr

Well-known member
Mar 31, 2013
181
TN
Hot and humid here for the last week or so. I was holding FC at 3-4 before the heat set in. In was running my IC40 10 hrs a day in my 44.5k gallons pool with it set on 80%. About two days ago I adjusted the run time to 12 hours and 90%. Last night checked it and the FC was 1. I added 2 gallons of leftover bleach from last year. This morning I checked it and the FC was 4.5.

I wonder if the cell is degrading or is the heat just getting the best of the FC level. I am running ph of 7.6, TA of 50, CH of 125, CYA of 50, and salt is 3400-3600.

Thoughts or recommendations?
 

Chrissykr

Well-known member
Jun 8, 2014
623
Rogers, AR
Re: FC dropping during hot days! Bad cell or normal?

The heat is getting the best of me right now. Chlorine consumption has shot up and I am holding off raising my CYA since I am going on vacation next month and need to use pucks.

I think your CYA is too low. In saltwater I believe they say 70-80.
 

txnole

LifeTime Supporter
Aug 18, 2014
544
Amelia Island, FL
Re: FC dropping during hot days! Bad cell or normal?

CYA for SWG pools is 60-80. Your swg is struggling at the low levels. Boost CYA and see if that helps.
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
993
Bunbury, WA, Australia
Re: FC dropping during hot days! Bad cell or normal?

Just wondering if the algae has gotten the better of you. It sounds like you have let your FC drop too low. Might be worth an OCLT to see whether it is something your going to need to hit up with a SLAM.
 

gobblerhuntr

Well-known member
Mar 31, 2013
181
TN
Re: FC dropping during hot days! Bad cell or normal?

I really don't think it's an algae attack. I pretty much test my water daily and yesterday was the first day it's been at 1. T

Think I might should raise cya now or do an OCLT night and see what that yields. If I remember right if he cya is lower when SLAMMING it requires less FC levels.
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
993
Bunbury, WA, Australia
Re: FC dropping during hot days! Bad cell or normal?

Well an OCLT will tell you one way or the other- so I would do that first before adding any CYA in. If you do end up having to SLAM then you will need more chlorine for the higher CYA level.

I'm truly hoping that your right and that you don't have any algae- I've been caught out like this a couple of times before in hot weather.
 

gobblerhuntr

Well-known member
Mar 31, 2013
181
TN
Re: FC dropping during hot days! Bad cell or normal?

About two days ago I adjusted the run time to 12 hours and 90%. My cya was 80 the only time I had to do a SLAM and it took a bunch of bleach to get it under control.

I'll do the test tonight.
 

gobblerhuntr

Well-known member
Mar 31, 2013
181
TN
Re: FC dropping during hot days! Bad cell or normal?

Well I passed the OCLT so it looks like I need to up the CYA to around 70.

Agree?
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
993
Bunbury, WA, Australia
Re: FC dropping during hot days! Bad cell or normal?

That's great news gobblerhuntr.

Yep crank it up -I would go for 80. Possibly in 2 steps if your worried about overshooting.
 

pooldv

TFP Expert
Platinum Supporter
LifeTime Supporter
Moderator Emeritus
Aug 10, 2012
25,412
FL panhandle
Re: FC dropping during hot days! Bad cell or normal?

+1 to going to 80 on CYA. CYA at 80 will lower your FC consumption noticeably .
 

gobblerhuntr

Well-known member
Mar 31, 2013
181
TN
Re: FC dropping during hot days! Bad cell or normal?

Yesterday my FC got to 1.5-2 so I added 2 gallons of bleach and did an OCLT. Last night the FC was ~5 (took 10 to 11 drops to clear up water) and this morning it was ~4-4.5 (took 9-10 drops to clear water). MY CYA is still around 50 as I haven't bumped it up yet. I need to either bump it up or SLAM?

Recommendations?
 

gobblerhuntr

Well-known member
Mar 31, 2013
181
TN
Just asking the obvious- did you switch your SWG off when you performed the OCLT?
Yes my pump run time stops at 8 pm and I did all test after 8 pm and before the pump kicked back on at 8 am.

That is correct right?

- - - Updated - - -

Keep raising CYA to 80. Dial back SWG slightly to maintain FC
I have the SWG set at 90% now. If I raise the CYA shouldn't I wait until the SWG is producing more FC than is used in a day then dial it back?
 

Jezza

LifeTime Supporter
TFP Guide
Jan 18, 2015
993
Bunbury, WA, Australia
To conduct a reliable FC test in the morning you really need to have the pump running beforehand- ideally around an hour to make sure the pool is mixed. You also don't want to wait too long between the pump turning off and testing at night. So this is what I would do

Test at night either with pump still running or straight after pump turns off
Set the pump to come on while for an hour before testing, allowing yourself enough time to test before the sun comes up

Also yes keep the SWG dialled up until you are confident that it is producing enough chlorine to maintain the correct FC for your CYA. When you are ready to move up to CYA of 80, then you need to closely monitor to ensure the SWG is keeping up with the required FC level. Remember you don't ever want to drop below the minimum FC. You could also consider adding an extra boost of bleach to help out the SWG.
 

Ksnewman

Silver Supporter
LifeTime Supporter
May 12, 2012
179
Middle Tennessee
Pool Size
30000
Surface
Vinyl
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
I have read that taking a sample directly in front of a return while SWG is on to see if you have a higher concentration. I keep my CYA at 80 in the summer and FC maintains around 6. Right now cell is at 75% and run time is about 6 or 7 hours a day. I only get about 6 - 7 hours of sun on the pool each day. If indeed your cell is going bad (check for scale) and you need to replace, you probably want to go to IC60 your cell may not be able to keep up with your size of pool.
 

PAGirl

TFP Guide
Jun 5, 2012
2,390
Central PA
The pump should be running for the OCLT at least an hour after adding for your double check to see you reached your target, and a half hour to hour before your morning check with the SWG off the entire night.
 

borjis

LifeTime Supporter
Aug 19, 2014
3,333
Pacific NW
is it just me or does the op have a barely sufficient swg? IC40 for a 44,000 gallon pool? I would not expect that to be sufficient.
 

gobblerhuntr

Well-known member
Mar 31, 2013
181
TN
I have always thought I needed an IC60.

Last night I added CYA and let the pump run all night to mix it. I tested the FC right after the pump shut off at its normal time and it was 3.5. This morning after running all night the FC was 3.5, that doesn't sound right to me. My cell has never had any scaling whatsoever and has been cleaned several times.

My pool started out as a 20'x40' then put Roman ends on each end so I consider it approx. 20'x48'x6' deep on average. Do y'all think that would be correct diminsions?

I now wonder if an IC60 will fit where the IC40 is?