Low FC

Deb04

LifeTime Supporter
Jul 12, 2008
338
Seacoast, NH
#1
Just looking for input.

I didn't test yesterday but I just tested and my FC is low. It usually runs at 5-5.5, and that's at the lowest setting (20%) on my SWG. My results are

FC 0.5
CC 0
PH 7.4
TA 70
CH 180
CYA 35 (working on getting that up)

So, that big dip in FC got my attention. I turned the filter back on, turned the SWG up to 40% and added 2 lbs of 65% Cal-Hypo. (Since my CH runs low, I keep that around for emergencies instead of bottled bleach.)

I'm thinking that this happened because of a combination of the series of sunny days we've had and my husband leaving the hose in too long yesterday, replacing evaporation. The water was just below the arrows on the skimmer and when he took it out it was above the skimmer. Evaporation has brought it down to just below the top of the skimmer today. Our fill water is bland, no chlorine, 7.0 ph, no CH, no metals.

If things aren't perfect with the water tomorrow I'm going to do a OCLT tomorrow night.

Water LOOKS perfect.

Would you recommend anything different?
 

Deb04

LifeTime Supporter
Jul 12, 2008
338
Seacoast, NH
#3
Re: Low FC - Update

Ackkkkk....So in the light of day this morning I saw that there was actually VISIBLE green algae on one of my pool walls. OMG. I've never had that before. I've had cloudy water when opened in the spring and a couple of times over four years Ive suspected I was on the verge of a bloom. I am horrified.

So, I added CL and I'm at FC= 18.5 and CC<.5. I've been brushing and brushing.

Two questions:
1. Any chance I'll pass the OCLT tonight? We have guests coming tomorrow and we'd like to let them swim.
2. My hubby accidently knocked the scissors I was using to open the Cal-Hypo bags into the deep end. I can't brush right around them because I don't want to poke a hole in the liner. He plans on diving in to get them. Is it safe with CL at shock levels if he's only in for a few minutes?

Thanks.
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
#5
Re: Low FC - Update

Deb04 said:
Ackkkkk....So in the light of day this morning I saw that there was actually VISIBLE green algae on one of my pool walls. OMG. I've never had that before. I've had cloudy water when opened in the spring and a couple of times over four years Ive suspected I was on the verge of a bloom. I am horrified.

So, I added CL and I'm at FC= 18.5 and CC<.5. I've been brushing and brushing.

Two questions:
1. Any chance I'll pass the OCLT tonight? We have guests coming tomorrow and we'd like to let them swim.
2. My hubby accidently knocked the scissors I was using to open the Cal-Hypo bags into the deep end. I can't brush right around them because I don't want to poke a hole in the liner. He plans on diving in to get them. Is it safe with CL at shock levels if he's only in for a few minutes?

Thanks.
Our guideline for safe swimming is up your FC shock level (depends on your cya), pool bottom clearly visible, and ph between 7.2-7.8. I also like CC <0.5 since some forms can cause eye and skin irritation. As for your husbands brief dive to retrieve the scissors, that should be fine.

As for swimming tomorrow, keep your FC high now and redose hourly. Tonight, when you do the OCLT, check FC (and CC) a couple of hours after doing the evening test to see where you are, if you are still loosing FC at that point you can dose all night long to keep killing the algae. Then tomorrow just follow the guidelines above for safe swimming.

Ohh, and brush, brush, brush often.
 

Deb04

LifeTime Supporter
Jul 12, 2008
338
Seacoast, NH
#6
Thanks.

Water is starting to look a little cloudy. Dead algae? Should I turn off the filter for a hour to let the algae settle on the bottom (note I can see dead algae on the bottom) and then vacuum?

I'm guessing that our solar cover now needs to be cleaned so my pool doesn't get reinfected. Any advice what to use to do that?

BTW, FC dropped only 0.5 in the last hour. Fingers crossed.
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
#7
Unless your filter pressure is going up to fast to clean the cartridges quickly enough, I would leave it on filter for now and keep circulating. Clean the cartridge when ever the pressure goes up 25% from your clean filter pressure.
 

Deb04

LifeTime Supporter
Jul 12, 2008
338
Seacoast, NH
#8
The pressure isn't going up at all. The PB gave us (as in sold us without discussion for which I am very thankful) an oversized filter and an oversized SWG.
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
#9
Deb04 said:
The pressure isn't going up at all. The PB gave us (as in sold us without discussion for which I am very thankful) an oversized filter and an oversized SWG.
Sounds good, just curious what size cartridge filter do you have?

If you have algae that is pooling on the floor, I would vacuum it to waste if you can do that.
 

Deb04

LifeTime Supporter
Jul 12, 2008
338
Seacoast, NH
#10
Hmmmmm, not sure how to answer. Specs on the label:
Sta-Rite system 3
Model s7m120
300 sq ft filtration area
Rate 0.33 gpm/sq ft
Max flow rate 100 gpm

Does that answer?
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
#11
Deb04 said:
Hmmmmm, not sure how to answer. Specs on the label:
Sta-Rite system 3
Model s7m120
300 sq ft filtration area
Rate 0.33 gpm/sq ft
Max flow rate 100 gpm

Does that answer?
Yep that answers it. Your cartridge filter is 300 sq. ft. and is right at the minimum we would recommend for you pool, so the good news is your set there :goodjob:
 

Deb04

LifeTime Supporter
Jul 12, 2008
338
Seacoast, NH
#12
Surprised it's at the min. PB told us it was oversized. I certainly get his motivation to stretch the truth, but we have been able to go each summer with no rise in pressure. I believed PB because of this.
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
#13
No the PB was right compared to the rest of the industry, he doubled the size. Here we suggest double as a minimum....so you did right by him.