Free Chlorine Too Low?

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
Hello TFP,

I drained my pool recently because my CYA was through the roof (300+) but now I seem to be having trouble with having enough FC.

Here are the rough numbers:

Total Hardness: 500
TC: 0.5
TB: 1
FC: 0? maybe 0.5
PH: 7.8
TA: 180
CYA: 30

Attached is a pic of the test. Right now I have about 3 tablets in the pool, Do I just need more or should I shock the pool for the FC to stay? Before when I had high CYA I was able to have 1, maybe 2 tablets in for weeks.

Thanks!
 

Attachments

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
23,701
Laughlin, NV
You need a proper test kit, see Test Kits Compared. I suggest the TF-100 A proper test kit is needed to get the accurate water chemistry results needed to follow the TFP protocols.
While you are waiting on your test kit, add 3 ppm FC worth of liquid chlorine / plain bleach to your pool each evening with the pump running. This will replenish the FC lost each day to the sun and keep any algae that may try to start growing.
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
I did just ordered a TF-100 actually.

I do have some granule trichlor and 3" chlorine tablets that I bought before I joined the forum. I planned on switching to Bleach/liquid chlorine once these are gone. Can I still use the trichlor and 3" chlorine tablets or should I just toss that stuff?

Either way, i'll pick up some liquid chlorine/plain bleach this afternoon.

Thanks!
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
So according to the PoolMath calculator I put in about 81oz of 10% liquid chlorine which was a little more than half the gallon. I'll check tomorrow to verify the FC it around 3ppm.

I bought the 2gal of 10% liquid chlorine from Home depot for $9. If this is a normal thing (I don't even want to think about the summer) then it's going to be about $9 every 3 days; seems like a lot compared to the 3" chlorine tablets that have CYA in them as well. Is it normal to use that amount of liquid chlorine/bleach every day or once I get the chemicals balanced will it be better?

Don't use any of those products you still have if any of them are labeled "Blue" or "XtraBlue" as they contain copper. Ugh!

Maddie :flower:
Good to know. I just checked and I have the stuff that doesn't have anything "Blue" related on it.
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
892
Spring Valley, NY
Not sure what you're buying but homedepot has pool shock chlorine 3 gallons in a box for about $10. You can change your pool over to SWCG and be done with the liquid chlorine thingy. Initial outlay dollar wise is there but over the life time of the cell you're about even with chlorine for that time period except you're not lugging the stuff home all season long and that's a lot in Arizona.
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
Not sure what you're buying but homedepot has pool shock chlorine 3 gallons in a box for about $10. You can change your pool over to SWCG and be done with the liquid chlorine thingy. Initial outlay dollar wise is there but over the life time of the cell you're about even with chlorine for that time period except you're not lugging the stuff home all season long and that's a lot in Arizona.
I've seen the 3 gallon box for $10, unfortunately they don't sell it at any home depots near me. I was looking at a SWCG but didn't pull the trigger, maybe I'll take a closer look.
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
12,433
Evans, Georgia
Don't overlook Walmart's Pool Essential liquid chlorine- $3.64 for gallon of 10%, and fresh. You always want to check date codes on liquid chlorine and only buy that which is no older than 60 days. The newer it is the stronger it is.
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
Walmart did have liquid chlorine so I grabbed 4 1gal jugs, Looks like the date was 2020-35, so it doesn't seem crazy old, but not super new.

The TF-100 should get here tomorrow so I'll try and use it to test the water tomorrow night.

In the mean time I have about 7 gallons of 10% liquid chlorine. If I'm keeping my FC at 3PPM, 7 gallons should last me between 1 to 2 weeks. I was hesitate to stock up on a ton of liquid chlorine because I know it degrades over time, Is that something I should really worry about or do you think I should just stock up?

Thanks again for all the help!
 

YippeeSkippy

Mod Squad
LifeTime Supporter
Jan 17, 2012
12,433
Evans, Georgia
You do have a fairly big pool..... it takes more of any chemical you add. At least you're not dealing with algae, right!

Get your TF-100 and start testing. Keep a record of your tests so you can spot trends.
FC
CC
pH
TA
CH
CYA

Also run the pH, TA and CH on your fill water so you know what your baseline is. That's handy.

Pool Math says ~1 qt of 10% liquid chlorine will raise your FC by 1ppm. <gosh I love PoolMath!> It will take ~44 ounces of 6% to raise FC 1ppm. And for 12% its ~22 ounces.

Maddie :flower:
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
You do have a fairly big pool..... it takes more of any chemical you add. At least you're not dealing with algae, right!
You are right, at least I don't have algae!

Get your TF-100 and start testing. Keep a record of your tests so you can spot trends.
Got the TF-100, here are the results:
FC - 6
CC -0
pH - 8.2
TA - 190
CH - 300
CYA - 50

Based on the CYA of 50 I should have 6-8ppm of FC. Since I'm at 6 now, I figure I'll put in 1qt to bring the FC up to 7ppm.

Also run the pH, TA and CH on your fill water so you know what your baseline is. That's handy.
I'll test that now.

So next steps as I see it:
  • Remove the 3" tablets since they have CYA and I don't need anymore CYA.
  • Put 1qt of chlorine in tonight to bring the FC to 7ppm.
  • Put Muriatic acid in to bring the pH and TA down, aerate the water to bring pH back up?

PoolMath says to put 114oz of 31.45% muriatic acid int to drop the pH to 7.1, then aerate the water to bring the pH back up.
How long should I aerate the water for though? Do I just need to periodically check the pH and TA to make sure they are within range while I aerate?

Thanks!
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
892
Spring Valley, NY
With a TA of 190 the PH is going to be beyond 8.2 but it registers max 8.2. DO NOT DUMP all that MA in one shot but rather split it up into 4 batches and keep checking in-between. CYA of 50 is good for now but as the summer heat will approach you may need it as high as 70-80.
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
With a TA of 190 the PH is going to be beyond 8.2 but it registers max 8.2. DO NOT DUMP all that MA in one shot but rather split it up into 4 batches and keep checking in-between.
Okay, I'll make sure split the MA up. How long should I aerate the water? couple hours, whole day? I don't want to aerate it too much and have the pH go up too high.

CYA of 50 is good for now but as the summer heat will approach you may need it as high as 70-80.
Okay, I'll plan on putting the 3" tabs back in when it gets closer to summer to raise the CYA.

Thanks for the help!
 

wireform

Silver Supporter
In The Industry
Aug 15, 2017
892
Spring Valley, NY
Aerate the pool as long as it needs to come back up to mid 7s. You can first try not to aerate and let it come back on its own as I think it'll happen with the high TA.
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
I started added in MA slowly and the pH kept coming down. I'm now aerating the pool to get the pH back up to mid 7s and I'll keep at it until the TA is around 100.

Thanks for the help everyone!
 

Cwiggs

Active member
Aug 31, 2019
31
Phoenix, AZ
So I've put in a total of about a gallon of MA and the pH was at about 7.2, I've been aerating for about 4 hours and the pH is around 7.5. I checked the TA and it's at about 120-130, so once the pH gets a little higher I'm gonna throw some more MA in to bring the TA down to 100, and the pH around 7.2-7.5

I also checked the FC and it's at 1ppm. I haven't added any bleach in 5 days, so it looks like I'm loosing 1ppm per day. I'm gonna throw in some bleach tonight to bring it back to 6 or 7 ppm and keep adding about 30oz of 10% bleach each day.

I feel like I'm getting a hang of this.