New and confused about FC level

[jmckee22]

Hey guys, I’m still trying to figure out my pool. Thanks so far to everyone who has helped. I understand so much more now and have read pool school.

I’m still confused by something and I’ll do my best to give you all the info.

22ish k gallon saltwater pool
Superpro 40k max SWG (1 year old)
Chlorinate % has been set at 75% since summer started
Salt 3000 (added 1 bag salt today)
Southeast US

TA 120
pH continuously going above 8. I check it daily and have added over a gallon of MA in the past week (usually 2-3 cups per day). Checked again today and above 8.
Calcium 330
CYA 50 (I added two bottles of liquid stabilizer a week ago because it was at 12)

Here is where I’m confused. I tested FC several days ago with the Taylor test kit and used the 25mL mark .2 per drop. A few days ago the pink color went clear at 50 drops. Two days ago it took 60. Today it took 70!? When I added 5 drops to check combined chlorine, the water DID NOT turn pink. I also turned DOWN the chlorinate % from 75 to 60 a few days ago. I haven’t added any chlorine. I haven’t turned on the super chlorinate. We’ve had a few big rain storms in the same few days.

So my two questions: what the heck do I do about my Free Chlorine. Why would it be rising? Could it be since I added cya my pool is now retaining chlorine and also producing it from the SWG?
Will I always have to add MA each day? I understand a lot of people add it weekly but daily is wild to me.

Thanks!

 

[thetekgeek]

Your chlorine is rising because the SWG is set higher than it needs to be. Good job on turning it down, keep adjusting it until you find the sweet spot where the chorine remains stable. You can adjust % output as well as pump run time until it finds the balance. I have to adjust my output a few times per season depending on the conditions. Also, for FC testing, use a 10ML sample and each drop will be .5 PPM. That will save reagents and still provide the consistency necessary for FC testing.

While your FC is > 10, your PH test becomes much more error prone. Try not to make PH adjustments while FC is greater than 10. That could be why your PH test is consistently high. However, with TA at 120 your PH will rise on its own relatively quickly. Each addition of acid should help to drive the TA down a little at a time. Over time, the TA should get to the point where the PH will become much more stable. In my (vinyl) pool, I have found that TA right around 70-80 the PH will stay pretty stable at around 7.8. If you wanted, or are bored and just want something to do you could treat PH down to 7.2 and then aerate the water to force the PH back up to 8 a few times to artificially force the TA down below 80. I don't think you really need to at this point though. You can just treat the PH when it gets above 7.8 down to 7.4 or 7.5 and let that process happen naturally.

 

[jmckee22]

Awesome! Thanks for the detailed response. I just turned my swg down to 50 and will monitor my levels.

 

[proavia]

Use the 10 ml sample size - each drop of R-0871 equals 0.5
Use 1 rounded/generous scoop of R-0870 powder
More than accurate enough and saves on reagents