FC and pH Struggle

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D

Denney

Member
Jun 24, 2023
7
Illinois
Opened pool 3 weeks ago and can't get numbers to stabilize. This is our first full year with pool so we're also still learning. Since opening we've only had 3 days when pH was normal, the other days it's been at a minimum or low. Our calcium has been very low (18) but we've been able to raise it. Now the FC is .5. Yesterday we added 7 cups of liquid chlorine. It's still .5. We added another 9 cups today and it's still .5. Pool math says to add another 6 cups.

Also the last 3 days we've put 2 lbs. per day of pool shock in. Suggestions please. Thank you!

15,000 gal chlorine fiberglass. Tested with Taylor TF-Pro kit. Use chlorine pucks. Auto cover.
CL .5
FC .5
pH 7.2
Calcium 200
Alk 120
CYA 40
 
Denney said:
Opened pool 3 weeks ago and can't get numbers to stabilize. This is our first full year with pool so we're also still learning. Since opening we've only had 3 days when pH was normal, the other days it's been at a minimum or low. Our calcium has been very low (18) but we've been able to raise it. Now the FC is .5. Yesterday we added 7 cups of liquid chlorine. It's still .5. We added another 9 cups today and it's still .5. Pool math says to add another 6 cups.

Also the last 3 days we've put 2 lbs. per day of pool shock in. Suggestions please. Thank you!

15,000 gal chlorine fiberglass. Tested with Taylor TF-Pro kit. Use chlorine pucks. Auto cover.
CL .5
FC .5
pH 7.2
Calcium 200
Alk 120
CYA 40
Click to expand...
Are you sure you have the right pool size set in pool math? Adding 7 cups to 15k gallons isnt going to do much.

Id do your calcium test again, would be almost impossible for it to have been 18ppm.
 
Sorry, I meant 118 on the calcium.

I rechecked pool math and the pool size is set correctly. We've been adding the amount of liquid chlorine it has been stating and it hasn't gone up. It doesn't seem like enough to us either but we also don't want to guess and just keep adding.
 
Denney said:
Sorry, I meant 118 on the calcium.

I rechecked pool math and the pool size is set correctly. We've been adding the amount of liquid chlorine it has been stating and it hasn't gone up. It doesn't seem like enough to us either but we also don't want to guess and just keep adding.
Click to expand...
Try adding one gallon and test it 15min later. That should add 6.7ppm FC. Is the water clear?

Note, your pool will likely consume 2 liters per day once summer hits full speed.
 
Your chlorine specs are hard to decipher.

Your FC (free Chlorine) should be at LEAST 3 (given your CYA level) and probably higher since
Your CC (Combined Chlorine is over .2.

7 cups of 10% chlorine would bring your pool to 3 PPM of chlorine, but apparently, something organic is trying to get a foothold in your pool. You need to superchlorinate your pool according to these instructions.
 
You are below minimum FC for your 30 CYA (which is 2.0 FC). This is not officially a trigger for SLAM Process but many would bring FC up to SLAM level regardless to be on the safe side.

If you choose not to bring FC to SLAM level - I would recommend that you at a minimum, add 14 cups 10% (which would be adding 6 FC) and perform the Overnight Chlorine Loss Test tonight/tomorrow morning. If for ease of measuring you add the whole gallon (16 cups), all the better.

If you do want to bring up to SLAM level, add 2 gallons 10%.
 
I added liquid chlorine after my last reading. I just did another reading:

FC 3.5
CC .5
Total Chlorine 4.0
pH 7.2
Calcium 200
Alk 120
CYA 30

I think I'm okay on the FC now, but my pH keeping hanging at 7.2. Earlier this week I added a box (a little at a time) of 20 Mule Team Borax to bring pH up but it only came up to 7.3 for one day then went back to 7.2. Should I add more Borax?

Should I be concerned about ALK and Calcium?
 

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