How do I keep my chlorine levels up with a SWG?

[SW Pool Owner]

I have an Autopilot RC-42 doing about 1.52 output per day.

I also have a ~42,000 - 45,000 gallon pool. I'm not quite sure because checking between schematics and actual pool there's some slight differences but this measurement has been what I've successfully used for chemistry.

I completed SLAM and now am letting FC levels drop from 30 -> 8. I'm noticing I'm losing somewhere around. 3 - 4 ppm FC a day. But how am I supposed to replace that much FC if my SWG produces such little chlorine? If I use the pool math calculator at 4 hours I'll have raised FC by 0.8. With 8 hours it's 1.5. I don't see how apart from running the SWG 24/7 I will match the FC loss. So does the FC loss come down the closer it gets to the level the CYA can support?

I started with a CYA of 0 pre-SLAM and have worked up to 50 CYA. I'm hesitant to get to 70 too quick but have the CYA ready to be added slowly over the course of 2 weeks because the CYA takes 48 hours to properly adjust.

This is my 2nd year with the pool and I FINALLY found the source of my algae and repeated SLAM, so I want to do this absolutely right and never worry about this pool again.

Test Results:
FC: 17.5->16.5ish overnight, I say ish because it's slightly higher than 16.5 as there's a tiny bit of pink left
Alkalinity: 70
pH: 7.6 Pre-slam, havent checked lately
CYA: 0 pre-slam, currently 50

Thanks

 

[mknauss]

With your pool volume, and that SWCG, you will need to run the pump 24 hours per day and the SWCG will need to be set at close to 100% generation to create the chlorine you will lose each day in mid-summer.

 

[SW Pool Owner]

Why I think I'm missing something is the previous house owner had this pool running with a smaller cell. So perhaps my measurements are off, but the chemistry has responded as predicted

 

[Jimrahbe]

SW,

A salt cell should be rated for at least 2 x the volume of the pool.. Your cell is way too small.

As Marty points out, you have to run 24/7 at 100%

Thanks,

Jim R.

 

[Jimrahbe]

Why I think I'm missing something is the previous house owner had this pool running with a smaller cell

SW,

I suspect that idiot was adding weekly bags of pool store shock. Sigh!!

Jim R.

 

[SW Pool Owner]

Ok do I have any options besides I'm SOL? I see there's a PPC5 AutoPilot Pool Pilot PPC5 / CC-15 Replacement Cell but I'm not sure how much FC it would produce. Also, there's no chance the FC loss per day in the sun goes down due to reaching equilibrium with the CYA, is there?

 

[ajw22]

Your SWG is undersized for your size pool.

Yes, you will need to run your pump 24/7 and your SWG on a high % to generate the necessary FC.

An average pool this time of your requires 3-4ppm of FC/day. Your FC demand is a normal level.

 

[ajw22]

Ok do I have any options besides I'm SOL? I see there's a PPC5 AutoPilot Pool Pilot PPC5 / CC-15 Replacement Cell but I'm not sure how much FC it would produce.

Ask the salt pool guys what the specs are on the PPC5.

The PPC3 (RC-42) that you have generates 1.52 lbs/day of chlorine and is sized for a 40K pool when run 24/7.

The PPC4 (RC-52) generates 2 lbs/day and is sized for a 60K pool when run 24/7.

I don't have the specs on the PPC5.

Also, there's no chance the FC loss per day in the sun goes down due to reaching equilibrium with the CYA, is there?

No. That is the loss for this time of year.

FC loss will drop as you get into the fall and winter as the sun angle decreases.

 

[SW Pool Owner]

Ask the salt pool guys what the specs are on the PPC5.

The PPC3 (RC-42) that you have generates 1.52 lbs/day of chlorine and is sized for a 40K pool when run 24/7.

The PPC4 (RC-52) generates 2 lbs/day and is sized for a 60K pool when run 24/7.

I don't have the specs on the PPC5.



No. That is the loss for this time of year.

FC loss will drop as you get into the fall and winter as the sun angle decreases.

Reached out, thanks.

Ok looks like I lied, sun's been shining all day and FC dropped by... 1? Went from 16.5 -> 15.5 FC. Based on what you guys said earlier, this seems highly unlikely and I guess I should repeat the FC test much slower tonight / tomorrow. For the FC tests I must confess I've been pouring drops while stirring and haven't really let each drop stir individually until the color got very light pink

 

[ajw22]

For the FC tests I must confess I've been pouring drops while stirring and haven't really let each drop stir individually until the color got very light pink

Drop size matters on all tests.

You need to hold the bottle vertically and let the drop form on the tip and naturally fall off. The tip is shaped to produce a standard drop size.

Do not squirt out drops. Just squeeze the bottle gently to let the drops form and fall off the tip.

Are you using a speed stir?

 

[SW Pool Owner]

Drop size matters on all tests.

You need to hold the bottle vertically and let the drop form on the tip and naturally fall off. The tip is shaped to produce a standard drop size.

Do not squirt out drops. Just squeeze the bottle gently to let the drops form and fall off the tip.

Are you using a speed stir?

I am not, just shaking while pouring.

Noted, will focus more on accuracy going forward. The FC got past shock level due to a misreading of CYA so wasn't too concerned about getting an exact reading but will be more careful now that im bringing it down and doing the OCLT

 

[ajw22]

I am not, just shaking while pouring

Get the Taylor Speedstir. It will make your testing easier and more accurate.

 

[SW Pool Owner]

Get the Taylor Speedstir. It will make your testing easier and more accurate.

To be honest as an extremely lazy person the batteries / pill weight / device look really annoying to manage / keep track of which is why I haven't considered it.

 

[SW Pool Owner]

Just heard back

"The PPC5 cell at 100% operation will produce 1000 gallons over its lifetime."

 

[ajw22]

To be honest as an extremely lazy person the batteries / pill weight / device look really annoying to manage / keep track of which is why I haven't considered it.

I find the swirling and inaccuracies a lot more annoying then set it up and let it swirl while I just put drops in and count.

 

[Mdragger88]

Stirring continuously during the test is not a problem. That is what the speed stir does. Squeezing the bottle & having alot of little drops is. As mentioned above keep the bottle vertical & let the drops come out. About a drop per second.
About your swcg- here’s approximately what it can produce in your 42k gal pool volume in 24 hours


You can play around with other #/day outputs to see what they would look like in your pool.
PoolMath effects of adding—> swg

 

[ajw22]

Just heard back

"The PPC5 cell at 100% operation will produce 1000 gallons over its lifetime."

That makes no sense.

You want to know the capacity of the cell to produce how many lbs of chlorine per day?

 

[Mdragger88]

To be honest as an extremely lazy person the batteries / pill weight / device look really annoying to manage / keep track of which is why I haven't considered it.

I keep mine in my kit all the time even while using it. I have the tf100 so it fits perfectly in one of the slots. I have accidentally thrown the pill in the yard a couple times when pouring out my sample/ rinse water

 

[SW Pool Owner]

Per the store, PPC3 can produce 300 gallons of chlorine. So about 3x the output with the PPC5 I assume. 4.5lb/s a day?

 

[Mdragger88]

Just heard back

"The PPC5 cell at 100% operation will produce 1000 gallons over its lifetime."

1000 gallons of what percentage of chlorine?
I have never heard it told that way. I have heard “replaces x # of trichlor” before.