CYA dropped and so did free chlorine

Pajara

Member
Jan 6, 2019
21
Tucson/arizona
So my CYA dropped to less than 20 after a long hot summer and now my free chlorine is only 0.5 and total chlorine 1.0. I have added CYA and it is now back up to 40 but my SWG has not raised the chlorine levels in a week. Any suggestions? Just cleaned the cartridge filter and salt cell today. Should I drop in a couple of pucks of chlorine to raise the levels back up. Chlorine level was good all summer with just the SWG cell providing it until the CYA dropped.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,463
Laughlin, NV
The SWCG is not designed to raise your FC levels. I suspect you have algae.

I suggest doing a Overnight Chlorine Loss Test. Add 10 ppm FC worth of liquid chlorine, circulate pool for 30 minutes, test FC, and then test FC in the morning before sun hits the pool surface.
 

RMcGirr83

Gold Supporter
Nov 19, 2018
433
Tuscola, TX
The SWG is for maintaining FC levels, not for raising them. Get some LC and boost the FC level up to where it's supposed to be for your CYA level.
 

Pajara

Member
Jan 6, 2019
21
Tucson/arizona
Thanks, I have added a couple of pucks of chlorine to my regular chlorinator and will also add bleach. Once I get my chlorine level back up the salt cell should maintain it?
 

Pajara

Member
Jan 6, 2019
21
Tucson/arizona
So I am at TH=250, TC=10, FC=7, pH=7.2, Total alkalinity=60 and CYA=50
If the chlorine levels stay the same over night am I okay? I know the pH is low but the pool is only 6 months old so I know the pH will creep up again. We had a lot of rain in the last month and the pool was running at 88 degrees so I know I will need to stay on top of it during monsoon season in the future.
 

RMcGirr83

Gold Supporter
Nov 19, 2018
433
Tuscola, TX
Is TH actually CH? The difference between TC (which I assume is total chlorine) and FC is 3 which isn't good and you probably need to do a SLAM as your CC levels indicate you have an algae issue.

What test kit are you using?
 

Pajara

Member
Jan 6, 2019
21
Tucson/arizona
Using Taylor K-1001 for free chlorine and pH and Taylor K-1000 for total chlorine. Checked levels again this morning for the overnight chlorine loss test and both my free chlorine and total chlorine are at the top of the color range so it looks like they are both reading 10 and the pH is still 7.2
Also did a quick read with AquaChek Select strips and got the same results. Looks like the CYA is between 50 and 100 on the strips.
Do I still need to SLAM?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,463
Laughlin, NV
While you are waiting on your test kit, add 5 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 also inhibit any algae in the water from growing further.
 

Pajara

Member
Jan 6, 2019
21
Tucson/arizona
Finished my SLAM, kept FC at 24 for 3 days, CYA was 50. Now CC=0.5 and OCLT was 1.0, water is clear can see heads on a quarter at 5 ft. 2 days latter Current test is CYA=50 TC=15 FC=15 pH=7.2 Total alkalinity=40 and CYA=50. Water temp has dropped to 83. I know my CYA level is low for a SWG pool, 70-80 recommended?
Which chemical should I adjust first Alkalinity or CYA level?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,463
Laughlin, NV
What is your CH? You can add 20 ppm TA worth of baking soda. How did your TA get so low?

No real need to raise CYA right now as we are entering winter. Just maintain your FC at 4 ppm or above with your SWCG until it stops producing for the winter then add liquid chlorine as necessary.
 

Pajara

Member
Jan 6, 2019
21
Tucson/arizona
MY CH is 300 which from what I understand is what to expect in Tucson AZ, we have really hard water. Fill water is at 250 out of the tap. We had inches of rain (lots of dirt in it from our dusty skies) and that is when the chemicals went out of balance. I probably got a little over zealous with the acid at that point. We still have swimming weather here 95 degrees so should I bump the CYA up a little too.