Why is Free Chlorine So High

[coryc3133]

Hi,

New pool owner here. It is a new build, plaster, Salt Water Pool. I've been reading TFP for months getting ready to take care of the pool myself. Since getting the SWG turned on for the first time (approx. 2 weeks ago, 30 days after it was first filled with water), the free Chlorine has been climbing very high unless I turn it off for several days. Last Wednesday (January 29th), it climbed up to 15.5. After turning off the SWG for several days, I got the free Chlorine to come down to 9.5 PPM on Sunday and Monday. Turned the SWG back on Tuesday morning at a lower level than initially set and recommended by the builder (65% from 8a-6p vs. 70% from 8a-8p that they recommended). I checked it today (Wednesday) at about 5:30p and it was up to 17.5 ppm. So an 8 PPM increase after having it back on for two days (from 8a-6p). Am I running it for too long? At too high of a %? My CYA is currently at 60 PPM. I've been testing with the TF-pro-100 test kit. Id appreciate any tips or insights people have.

Thanks!

 

[ajw22]

Welcome to TFP.

What model SWG are we discussing?

What % is the SWG set at and how long does it run daily?

How many gallons in your pool?

Basically run your SWG at a lower % or s shorter time or both.

PoolMath Effects of Adding can help you determine the amount of FC a SWG will give you for a % and daily run time.

SWG How It Works - Further Reading

www.troublefreepool.com

 

[toddclare]

Been hanging around here for just under a year and didn’t know about the SWG calculator in PoolMath. Great to know!

 

[ajw22]

Your pool probably does not need more than 2-3 ppm of FC daily. Maybe less.

Your FC needs increase as we get into the summer. So SWG runtime needs to be adjusted about monthly as the seasons change.

 

[coryc3133]

Its a Hayward Turbocell T5. The last few days I've been running it at 65% for 10 hours/day. It's a 9.3k gallon pool. According to the app, it should have only added 2.4 PPM per day at that rate:

 

[ajw22]

Its a Hayward Turbocell T5. The last few days I've been running it at 65% for 10 hours/day. It's a 9.3k gallon pool. According to the app, it should have only added 2.4 PPM per day at that rate:View attachment 627199

So over 14 days the FC climbed by 15. That means you are generating 1ppm per day too much.

Set the % so you get about 1.4 ppm per day. Test in 2 or 3 days. If FC is still rising then lower % more. If FC is dropping then raise %. Repeat until you get SWG % dialed in and FC being pretty stable.

 

[coryc3133]

So over 14 days the FC climbed by 15. That means you are generating 1ppm per day too much.

Set the % so you get about 1.4 ppm per day. Test in 2 or 3 days. If FC is still rising then lower % more. If FC is dropping then raise %. Repeat until you get SWG % dialed in and FC being pretty stable.

Okay, that makes sense. Thanks, that is super helpful!

 

[Jimrahbe]

Cory,

Just to be clear..

The SWCG has no clue how much FC is in your pool water..

It just generates the amount of chlorine that you tell it to generate.

It is dumb as a rock, and depends on your brain to control it...

Kind of like how my wife feels about me...

Thanks,

Jim R.

 

[Newdude]

The SWCG has no clue how much FC is in your pool water..

Nor the point in the season. Pretty soon in FL, the daily UV demand will match and then eclipse your over production that you're running now. There's always a whoopsie week in there somewhere but for the most part, it follows a schedule like a bell curve with daily FC loss.



Your frequent testing (YAY) will guide you based on last week's trends. The game is to match the UV loss for that point in the season with a little wiggle room for curveballs. A big storm, a particularly intense UV day or an impromptu swim party might need a little more than the day before.

You can drive yourself nuts micromanaging it, so most of us utilize the safety net between target range and SLAM. Notice the 'room for error' above target range up to SLAM, and how little wiggle room there is below target range. The closer you run to min, the closer you need to pay attention.



Obviously, depleting cell life with too much runtime is a concern, so don't let it run wild, but if it's a couple ppm above target, let it be. I shut mine off when FC hits a teen and let it drift down to target range before firing it up again. That'll happen much sooner in July than it will in April or Oct.