CYA, FC and pump run time.

pb4uswim

Well-known member
Jul 23, 2020
91
Michigan
Today's results are:

PH - 7.6
FC - 5
CC - 0
CH - 225
TA - 90
CYA - 40

Things are looking pretty good, so I'm not making any big changes at this time. I've been struggling with the CYA test, but I feel that the result is good now and am adjusting my FC up slowly. Because I'm using a SWG, it will take a few days because I don't want to go way over. Plus, I'm going to do two things. First, I'm turning up the generation percentage. I'm only at 40% right now. I'll probably go up to 60%. Then, I want to back off my pump time. I'm currently running 16 hours (4 hours on high and 12 hours on med). I'd like to get that down to at least 12 hours and maybe less.

Thanks for the help so far.
 

CrystalRiver

Well-known member
Jun 19, 2020
385
Massachusetts
Your CYA is way low for a SWCG pool. Get that to the right level before you dial in your generator. Having more CYA will change how much you need to run the generator.
 

Msch99

Gold Supporter
Bronze Supporter
Jun 11, 2018
908
Verona, MO
Yup, raise cya to 70. Once you reach the proper FC level the chlorine loss per day will about the same though. Just need more if need to slam.
 

pb4uswim

Well-known member
Jul 23, 2020
91
Michigan
So a few days ago, I posted my numbers and FC was about 7 and CYA was around 40. I thought I was doing fine but that was because I was reading the wrong table. The one for non-SWG. So, the recommendation was to boost my CYA up to 70. I’m in the process of adding CYA, but in the meantime, I am wondering about the balance of FC and CYA at various pump run times.

The base question is, should I set my pump to run longer and at a lower generation percentage or should I run the pump the minimum needed to clean the pool and have the generation percentage set at the high end.

My gut tells me that if a SWG pool should have a high CYA and a lower FC, the expectation is that one is running the pump longer and generating at a lower percentage. This seems consistent with the recommendation. Otherwise, why wouldn’t a SWG person just mimic a non-SWG pool and dump a lot of chlorine in and shut the pump off. On the same note, why wouldn’t a SWG, run a high FC and a lower CYA? After all, it’s not like I’m buying chlorine by the gallon.

The basis for all this is that I’m uncomfortable taking CYA up so high but I’d like to run my pump the minimum hours per day and I’m not sure how to balance the conflicts. With a VSP, maybe I should just run it slow on a low generating percentage, which seems the expectation of a high CYA, low FC recommendation.
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
34,777
Laughlin, NV
Even at 100% generation, you will be running your pump about 8 hours a day. So that is fine if that is what you would like to do. The elevated CYA is to protect the FC during the daylight. But you can run the pump at anytime you like.
 

CrystalRiver

Well-known member
Jun 19, 2020
385
Massachusetts
You may not be buying by the gallon, but your chlorine still costs. Electricity to run the pump, electricity to run the generator, the cost of the generator in the first place and replacement cells over time.
 

Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,300
Bedford, TX
run a high FC and a lower CYA? After all, it’s not like I’m buying chlorine by the gallon.

pb4,

Well you kind of are... Cell's can only produce so much chlorine and then, they die.. If you run a low CYA, the pool will use more FC, so your cell will have to generate more chlorine, basically using the cell up quicker.

As long as the cell's flow switch is closed, it does not matter what speed the pump is running.. In my case 1200 RPM allows me to generate chlorine and skim my pool.. I only run faster if I turn on my waterfall or want to have that lazy river feel when using the floats.

Thanks,

Jim R.
 

pb4uswim

Well-known member
Jul 23, 2020
91
Michigan
Even at 100% generation, you will be running your pump about 8 hours a day. So that is fine if that is what you would like to do. The elevated CYA is to protect the FC during the daylight. But you can run the pump at anytime you like.

I guess I will try it out, but my guess is that either it's because the cell is new or it's oversized for my pool. I've been running it 16 hours (4hrs at 90% pump speed and 12hrs at 60% pump speed) with the generator at 20% and I'm holding FC above 5%. I moved the generator up to 40% and I hit FC of 8 in one day. I'll get my CYA up to at least 60 and then move the pump down to 8 hours and see what happens. I think I'll move the generator up to 75% for my first test.
 

pb4uswim

Well-known member
Jul 23, 2020
91
Michigan
pb4,

What is your purpose in running your pump so fast?

Thanks,

Jim R.

I'm new to this so the honest answer is that I don't know. I guess I figured that having it on high for a few hours would "clean" the pool while the rest of the time it would just be good to have it circulating. Sounded good to a rookie. :)

Actually, now that you make me think about it, I changed it from running 24/7 at 50% (the way the installers programmed it) to the 4hr @ 90% and 12hr @ 60% because mathematically, that was equal while allowing it to be off at night. That too may not make sense, but that's why I did it.
 

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Jimrahbe

Mod Squad
TFP Expert
LifeTime Supporter
Jul 7, 2014
20,300
Bedford, TX
pb4,

There is no right answer here, as it is up to the pool owner how he runs his pool... But.. It seems to me the whole point of having a VS pump is to run it as slow as you can and still get the results you want.. In my case, I run my pump 24/7, most of the time at 1200 RPM, for less than $20 bucks a month...

I do this because I like to generate a little chlorine all the time and I like skimming all the time..

It is certainly not a requirement, but just something I like to do..

Thanks for the honest answer to my question.. :thumleft:

Jim R.
 

pb4uswim

Well-known member
Jul 23, 2020
91
Michigan
Thanks for the input. I’ll look into that. I’ll have to see if there’s a reference to the rpm’s somewhere. All I see is percentages. So if I run on med, it’s 50%. I can adjust the percentage infinitely so I’ll probably be able to find a max rpm in the manual and go from there.
 

pb4uswim

Well-known member
Jul 23, 2020
91
Michigan
Just an update. I’ve been raising the CYA. I’m at 60 and maybe a bit more. Not quite at 70 as I can still see the dot at 70, but it’s gone by 60. My FC is 5.5 today and my CC is zero to .5 (no more than one drop needed for sure to get to clear). I think I’ll put in another pound of CYA in a day or so and see where I’m at then.

FWIW, the pool is clear and whatever I had early on was either not algae or it’s been killed. Either way, I haven’t seen anything on the bottom for well over a week now. Very happy about that as I was dreading the thought of dealing with yellow algae.
 
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