Trouble with SWG and FC

randys

Gold Supporter
Oct 28, 2018
77
Clayton, NC
This is our first spring with the pool and our first season with the SWG plugged in. When we first put salt in about a month ago I had the SWG set to 85% and the FC was creeping up steadily too high. Right now I have 65CYA and am aiming for 8FC. FC was getting up to 10 and still climbing so I reduced the SWG down to 15% to let it drop and then brought it up to 50% once it did. About the same time, we started getting very heavy pollen, lots of rain and quite a bit of wind. But now at 50%, the FC keeps dropping down to 6.5. I'll throw in some liquid chlorine to bring it to 8 and the next morning it will be at 7.8 and by the end of the day even more lose. It's not keeping up. Today I just raised it up to 85% again, but I don't know what's going on. The water is VERY clear, but the the skimmer sock keeps filling up with what I think is pollen (lots of it, even within an hour of changing it's almost full again).

It also seems like the SWG salt level reading has been going down as well. At one point it read 3200, but went back down to 2900. I threw in another 40lb bag (I forgot to turn the SWG off that time) and it brought it up, but it's back down at 2900. I haven't done a manual salt test in a while, so I don't know what it really is. We have an over flow pipe and it's possible that heavy rain reduces it. There was some serious rainfall the last week or so.

I guess my question is: Can pollen and wind do this kind of thing with FC?
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,475
Northern NJ
Anytime your SWG shows low salt you need to confirm it with the K-1766 Salt test. The salinity test is often the first thing to get flakey in a SWG. You can't trust it if it shows lower salt then you expect.

Pollen will consume FC. Wind will not but wind can blow organics into the pool that will consume chlorine.

Your CYA is 70 and your FC target should be 8-10. When you have conditions like high pollen you should run your FC 1-2ppm on the high side of your target. That way you are not constantly having to adjust the SWG to keep it from fallen below your target.

You can not eyeball a CYA of 65. The scale between the lines is logarithmic, not linear. We always round up. So if the dot disappears between the 70 and the 60 line, then you call it 70.
 
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randys

Gold Supporter
Oct 28, 2018
77
Clayton, NC
Yeah.. It's hard to know if the dot is considered disappeared, because I can always stare long enough to see it :) Maybe I need more CYA.

This is what the sock is filling up with, it feels almost like a lint like fiber:
98087

I'll test salt tonight.
 

randys

Gold Supporter
Oct 28, 2018
77
Clayton, NC
It's that plus pollen. Pollen here is really bad in April. I was on a flight home a few weeks ago and could see the yellow in the ponds from above. I was gone for a whole week, you should have seen the skimmer sock when I cleaned it out after that. Also, it accumulates all over our deck and concrete. Then there are these pollen buds and small sediment that fall from the trees that land in the pool, especially on these windy days.

I really do hope the issue is the pollen. I run the pump from 8am-12pm and then from 4pm-8pm. Lately, the first 4hrs hours the pump is running may also be too cold to generate chlorine as the air has been in the 40F's and the water can get to the 50Fs at night. I guess there are a lot of variables at play but by mid day the water is 70F.
 

ajw22

Gold Supporter
TFP Guide
Jul 21, 2013
10,475
Northern NJ
I run the pump from 8am-12pm and then from 4pm-8pm. Lately, the first 4hrs hours the pump is running may also be too cold to generate chlorine as the air has been in the 40F's and the water can get to the 50Fs at night. I guess there are a lot of variables at play but by mid day the water is 70F.
Your SWG may not be having enough runtime to give you the needed daily FC due to shutting down when the water is cold. Maybe you need to run your pump longer after 8PM when the water is still warm from the day.
 

setsailsoon

LifeTime Supporter
TFP Guide
Oct 25, 2015
1,549
Stuart/FL
Randy,

Allen's got it right. Treat your CYA as 70 and definitely test salt level. The reading on mine fluctuates a lot. Seems to have one reading that's instantaneous and one that's a running average. Usually runs lower than my test strips by a couple hundred ppm.

I just started up a salt pool as well. I think you will do better to take smaller steps and use Pool Math to help. Based on your description it sounds like 85% was definitely too high and 50% might have been a little too low. I put your pool size and salt cell into Pool Math to see what it's giving and it says you're pretty close.. If you run it 7 hrs per day 55% you'll be adding 1.5ppm. Try this then move % up and down 5% at a time. I think this should be a good starting point for you this time of year. Once you get the % locked in you can fine tune FC level with run time.

Pollen does affect the chlorine demand but not as much as you'd think because most of it floats on the surface and get trapped in the filer basket liner you are removing. Keep removing it, everything you remove will reduce impact to FC.

I hope this is helpful and please do ask any other questions if you continue to have problems getting the FC in control.

Chris
 

setsailsoon

LifeTime Supporter
TFP Guide
Oct 25, 2015
1,549
Stuart/FL
Your SWG may not be having enough runtime to give you the needed daily FC due to shutting down when the water is cold. Maybe you need to run your pump longer after 8PM when the water is still warm from the day.
Very good point Allen makes. I'm way down here in S Florida with year-round pool. Easy to forget you can be under 60 deg up there. Pretty cold for this cold weather wimp!
 

randys

Gold Supporter
Oct 28, 2018
77
Clayton, NC
Resolution: So yes. You are all right. I tested salt this morning, exactly 3000. Yesterday I also increased the SWG to 85% for the last 4hrs it was running (at that stage, it's a good temperature). This morning the FC was 8.2, up from 6.5 all on its own! This morning the water was also 55F! So yes, it has been the case that when the SWG was set to 50% it was generating nothing the first 4hrs (too cold) and then operating 50% for only 4hrs a day (effectively 25% for 8hrs).

I set the pump back to 50% (PoolMath App Recommendation) and modified the 8hr pump-run time to be 12pm-8pm (8hrs good temperature).
 

PoolGate

Gold Supporter
TFP Guide
Jun 7, 2017
3,795
Damascus, MD
I run my pump 24x7. 3000rpms from 6am to 8am to get a good skim and 1500rpms the rest of the time except if we are swimming and want to use the waterfalls. Running a VSP 24x7 on low speed makes it a lot easier to dial in the SWG. During the season I keep mine at 52%. It sometimes drifts up to 15 parts chlorine but no biggie I just turn it down and let it drift. You are safe to swim in chlorine up to your SLAM levels.
 

EdKuhn

Silver Supporter
Jun 22, 2018
70
Concord, NC
Yeah.. It's hard to know if the dot is considered disappeared, because I can always stare long enough to see it :) Maybe I need more CYA.

This is what the sock is filling up with, it feels almost like a lint like fiber:
View attachment 98087

I'll test salt tonight.
Looks like my skimmer socks every day lately, sometimes twice a day (I use hairnets). Pollen is like a fifth season in NC :cool: I think it's dying down now at least!
 

randys

Gold Supporter
Oct 28, 2018
77
Clayton, NC
I run my pump 24x7. 3000rpms from 6am to 8am to get a good skim and 1500rpms the rest of the time except if we are swimming and want to use the waterfalls. Running a VSP 24x7 on low speed makes it a lot easier to dial in the SWG. During the season I keep mine at 52%. It sometimes drifts up to 15 parts chlorine but no biggie I just turn it down and let it drift. You are safe to swim in chlorine up to your SLAM levels.
Safe to swim in, but consistently high fc levels will beach the liner, right?