Baffling Chlorine Issue

[Florida Ron]

Long story short, I have been battling with keeping chlorine in the pool. From what I can tell, everything seems OK.

FC seems to be steadily going down for whatever reason but never more than 1 ppm overnight.

FC 2.5
CC 0
pH 7.6
CH 500
TA 90
CYA 70
Salt 4600

I inspected the cartridge filter and there is a small crack in the top of it. Could this be causing the issue? The manufacturer is supposed to be coming next week to replace it. Also, the SWCG has been tested and is fully functional.

 

[tim5055]

OK, I see in another post you are testing with a TF-100.

Have you followed the full directions for the Overnight Chlorine Loss Test? I would run the test again, supplementing the SWCG with bleach before the PM test to get the FC above 5 before you test.

I doubt the cracked filter cap is the cause.

If you add the details of your pool to your signature it would help us make other suggestions.

 

[Florida Ron]

That's weird. The first thing I did was update my signature when I signed up. I'll update it again later when I'm off the road. In the meantime, here is what you need.

Yes, I tried the Overnight test and it never goes down more than 1 ppm, then creeps up a little during the day and then drops a little overnight.

Pool details
13,000k gallon
Pebble finish
SGS Salt system rated for 40k gallon pool
Hayward 2 speed pump
Hayward cartridge filter

 

[Griswald]

With a CYA of 70, you should have much higher FC. Use some bleach to get it up over 5.0 and let the SWG hold it there. Your SWG might not be able to create enough chlorine to raise your levels, but should easily be able to hold your levels.

 

[duraleigh]

I am not sure why you are puzzled? Chlorine is consumable and constantly needs to be replenished.

When you do the OCLT, do you shut off the SWG?

read "The ABC's of Pool Water Chemistry" up in Pool School for good defintions of ALL the pool parameters.

 

[Sidecarist]

I have run my pool at 70 cya but keep my FC target at 4.5 for an afternoon test. It will drift down to 3.5 by the morning, but there is some swimmer load in the evening and the afternoon sun gets some. My pump & swg run 5 hours during the day to bring the FC back to target before swimming, and I never drop below 3.5FC, and if all is running well I can test in the morning and have a CC of 0.5 as the chlorine hs been doing its work overnight. If I test for CC after the pump shuts down its always 0.

My bump up your target to 4.5 or 5 FC and then dose the pool with bleach to get it there. Keep an eye on the levels and adjust the swg or run time to maintain the target level.

 

[tim5055]

First, you either need to up your run time or increase your SWG %. With 70 CYA you never want to go below 3 for FC and keeping it about 5 is better.

You don't list the exact SWCG you have, but is it sized properly for the pool? For your pool a 40,000 gallon unit is about right as you down want to run it all,the time or at 100% if at all possible.

But, with all,that being said, Dave is correct - chlorine is a consumable item. It gets used up all the time.